Indole derivatives as 5-HT1-like agonists

ABSTRACT

Compounds of formula (I) and pharmaceutically acceptable salts thereof, wherein R 1  is a substituted alkylene; C 3  -C 7  cycloalkyl optionally substituted with HO; C 3  -C 6  alkenyl optionally substituted with aryl; C 5  -C 7  cycloalkenyl; or C 3  -C 6  alkynyl; R 2  is H; halo; F 3  C; NC; R 8  R 9  NOC; a substituted alkylene; R 8  R 9  NO 2  S; R 10  S(O) m  ; R 12  CON(R 11 ); R 10  SO 2  N(R 11 ); R 8  R 9  NOCN(R 11 ); R 10  O 2  CN(R 11 ); R 13  (CH 2 ) n  CH═CH; or R 7  O are selective 5-HT 1  -like receptor agonists useful in the treatment of migraine, cluster headache, chronic paroxysmal hemicrania and headache associated with vascular disorders.

This application is a National Stage application of PCT/EP93/00738 filed Mar. 25, 1993 and published as WO 93/21177 on Oct. 28, 1993.

The present invention relates to indole derivatives which act on 5-hydroxytryptamine (5-HT) receptors.

More particularly the present invention relates to 3,5-disubstituted indoles which are selective agonists at the "5-HT₁ -like" subtype of the 5-hydroxytryptamine receptor. Such "5-HT₁ -like" receptors are present in the carotid vascular bed and their activation causes vasoconstriction with a consequent reduction in carotid blood flow. Compounds which have "5-HT₁ -like" agonist activity are therefore useful in the treatment of medical conditions which are thought to result from excessive dilation of the carotid bed, such as migraine, cluster headache, chronic paroxysmal hemicrania and headache associated with vascular disorders. Certain compounds of the present invention are also agonists at central 5-HT₁ receptors and are therefore useful for the treatment of depression, anxiety, eating disorders, obesity and drug abuse.

The present invention provides compounds of formula: ##STR2## and pharmaceutically acceptable salts thereof, wherein

R¹ is (R³ CO) C₁ -C₃ alkylene; (R⁴ O₂ C) C₁ -C₃ alkylene; (R⁵ R⁶ NOC) C₁ -C₃ alkylene; (R⁵ R⁶ NO₂ S)C₁ -C₃ alkylene; [R³ S(O)_(m) ]C₁ -C₃ alkylene; (R⁷ O) C₂ -C₄ alkylene; (C₃ -C₇ cycloalkyl) C₁ -C₃ alkylene; (aryl) C₁ -C₃ alkylene; (heteroaryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl optionally substituted with HO; C₃ -C₆ alkenyl optionally substituted with aryl; C₅ -C₇ cycloalkenyl; or C₃ -C₆ alkynyl;

R² is H; halo; F₃ C; NC; R⁸ R⁹ NOC; (R⁸ R⁹ NOC)C₁ -C₃ alkylene; R⁸ R⁹ NO₂ S; (R⁸ R⁹ NO₂ S) C₁ -C₃ alkylene; R¹⁰ S (O)_(m) ; [R¹⁰ S (O)_(m) ]C₁ -C₃ alkylene; R¹² CON (R¹¹); [R¹² CON(R¹¹)]C₁ -C₃ alkylene; R¹⁰ SO₂ N(R¹¹); [R¹⁰ SO₂ N(R¹¹)]C₁ -C₃ alkylene; R⁸ R⁹ NOCN(R¹¹); [R⁸ R⁹ NOCN(R¹¹)]C₁ -C₃ alkylene; R¹⁰ O₂ CN(R¹¹); [R¹⁰ O₂ CN(R¹¹)]C₁ -C₃ alkylene; R¹³ (CH₂)_(n) CH═CH; or R⁷ O;

R³ is C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl) C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl; or aryl;

R⁴ is C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; or C₃ -C₇ cycloalkyl;

R⁵ and R⁶ are each independently selected from H; C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; and C₃ -C₇ cycloalkyl;

or

R⁵ and R⁶ together with the nitrogen atom to which they are attached form a 4- to 7-membered heterocyclic ring which may optionally incorporate a further heteroatom linkage selected from O, S(O)_(m), NH, N(C₁ -C₄ alkyl), and N(C₁ -C₅ alkanoyl);

R⁷ is H; C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl; or aryl;

R⁸ and R⁹ are each independently selected from H; C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; and C₃ -C₇ cycloalkyl;

or

R⁸ and R⁹ together with the nitrogen atom to

which they are attached form a 4- to 7-membered heterocyclic ring which may optionally incorporate a further heteroatom linkage selected from O, S(O)_(m), NH, N(C₁ -C₄ alkyl), and N(C₁ -C₅ alkanoyl);

R¹⁰ is C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; C₃ C₇ cycloalkyl; or aryl;

R¹¹ and R¹² are each independently selected from H; C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl; and aryl;

R¹³ is selected from R⁸ R⁹ NOC; R⁸ R⁹ NO₂ S; R¹⁰ S(O)_(m) ; R¹² CON(R¹¹); R¹⁰ SO₂ N(R¹¹); R⁸ R⁹ NOCN(R₁₁); and R¹⁰ O₂ CN(R¹¹); wherein R⁸, R⁹, R¹⁰, R¹¹ and R¹² are as defined above;

and

k, m and n are each independently selected from 0, 1 and 2.

In the above definition, aryl means phenyl optionally substituted with one to three substituents independently selected from C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halo, F₃ C, NC, H₂ NOC, and HO; heteroaryl means pyrrolyl, furyl, thienyl, oxazolyl, thialolyl, pyridyl, pyrimidinyl or pyrazinyl; and halo means fluoro, chloro, bromo or iodo.

Unless otherwise indicated, alkylene groups having two or more carbon atoms, alkyl and alkoxy groups having three or more carbon atoms, and alkanoyl, alkenyl and alkynyl groups having four or more carbon atoms, may be straight chain or branched chain.

The compounds of formula (I) may contain one or more asymmetric centres and thus can exist as stereoisomers, i.e. as enantiomers or as diastereoisomers. Furthermore, compounds of formula (I) which contain alkenyl groups can exist as cis-stereoisomers or trans-stereoisomers. In each instance, the invention includes both the separated individual stereoisomers as well as mixtures thereof.

The preferred stereoisomers are those which possess the R-configuration at the 2-position of the azetidine, pyrrolidine or piperidine ring, as represented by formula (IA): ##STR3##

Also included in the invention are radiolabelled derivatives of compounds of formula (I) which are suitable for biological studies.

The pharmaceutically acceptable salts of the compounds of formula (I) are, for example, non-toxic acid addition salts formed with inorganic acids such as hydrochloric, hydrobromic, sulphuric and phosphoric acid, with organo-carboxylic acids, or with organo-sulphonic acids. For a review of suitable pharmaceutical salts, see J. Pharm. Sci., 1977, 66, 1-19.

A preferred group of compounds of formula (I) is that wherein R¹ is (R³ CO)C₁ -C₂ alkylene; (R⁴ O₂ C) C₁ -C₂ alkylene; (R⁵ R⁶ NOC) C₁ -C₂ alkylene; R⁵ R⁶ NO₂ SCH₂ CH₂ ; [R³ S(O)_(m) ]C₁ -C₂ alkylene; (R⁷ O)C₂ -C₃ alkylene; (C₃ -C₇ cycloalkyl)CH₂ ; (phenyl) C₁ -C₂ alkylene; (pyridyl) C₁ -C₂ alkylene; C₅ -C₆ cycloalkyl optionally substituted with HO; C₃ -C₅ alkenyl optionally substituted with phenyl; or cyclohexenyl; R² is R⁹ NHOC; (R⁹ NHOC)C₁ -C₂ alkylene; R⁹ NHO₂ S; (R⁹ NHO₂ S) C₁ -C₂ alkylene; R¹⁰ SO₂ ; (R₁₀ SO₂)C₁ -C₂ alkylene; R₁₂ CONH; (R¹² CONH)C₁ -C₂ alkylene; R¹⁰ SO₂ NH; (R¹⁰ SO₂ NH)C₁ -C₂ alkylene; or R¹³ CH═CH; R³ is C₁ -C₆ alkyl or aryl; R⁴ is C₁ -C₆ alkyl or (aryl)C₁ -C₃ alkylene; R⁵ and R⁶ are each independently selected from H or C₁ -C₆ alkyl; R⁷ is H or C₁ -C₆ alkyl; k is 1; m is 1 or 2; and R⁹, R¹⁰, R¹² and R¹³ are as previously defined for formula (I).

A more preferred group of compounds of formula (I) is that wherein R¹ is R³ COCH₂ ; R³ COCH₂ CH₂ ; R⁴ O₂ CCH₂ ; R⁴ O₂ CCH₂ CH₂ ; R⁵ R⁶ NOCCH₂ ; R⁵ R⁶ NOCCH₂ CH₂ ; R⁵ R⁶ NOCCH(CH₃); R⁵ R⁶ NO₂ SCH₂ CH₂ ; R³ S (O)_(m) CH₂ CH₂ ; R⁷ OCH₂ CH₂ ; R⁷ OCH(CH₃)CH₂ ; R⁷ OCH₂ CH₂ CH₂ ; cyclopropylCH₂ ; cyclobutylCH₂ ; cyclopentylCH₂ ; benzyl; phenylCH₂ CH₂ ; phenyl(CH₃); pyridylCH₂ ; pyridylCH₂ CH₂ ; cyclopentyl; hydroxycyclopentyl; allyl; pentenyl; cinnamyl; or cyclohexenyl; R² is R¹⁰ SO₂ CH₂ CH₂ or R⁹ NHO₂ SCH═CH; R³ is methyl or phenyl; R⁴ is (CH₃)₃ C or benzyl; R⁵ and R⁶ are each independently selected from H or methyl; R⁷ is H or methyl; R⁹ is H or C₁ -C₆ alkyl; R¹⁰ is C₁ -C₆ alkyl or aryl; k is 1; and m is 1 or 2.

A particularly preferred group of compounds of formula (I) is that wherein R¹ is CH₃ COCH₂ CH₂ ; (CH₃ )₃ CO₂ CCH₂ CH₂ ; benzylO₂ CCH₂ ; H₂ NOCCH₂ CH₂ ; CH₃ NHOCCH₂ CH₂ ; (CH₃)₂ NOCCH₂ CH₂ ; H₂ NO₂ SCH₂ CH₂ ; phenylSOCH₂ CH₂ ; HOCH₂ CH₂ ; CH₃ OCH₂ CH₂ ; cyclopropylCH₂ ; cyclobutylCH₂ ; cyclopentyl CH₂ ; phenylCH(CH₃); 2-pyridylCH₂ ; 4-pyridylCH₂ ; 2-pyridylCH₂ CH₂ ; cyclopentyl; 2-hydroxycyclopentyl; allyl; 3-methyl-2-butenyl; cinnamyl; or 3 -cyclohexenyl; R² is CH₃ CH₂ SO₂ CH₂ CH₂ ; phenylSO₂ CH₂ CH₂ or H₂ NO₂ SCH═CH; and k is 1.

In another aspect, the present invention provides processes for the preparation of compounds of formula (I) and their pharmaceutically acceptable salts.

A compound of formula (I) may be obtained by selective N-alkylation of the saturated heterocyclic ring of a compound of formula (II): ##STR4## wherein R² and k are as previously defined for formula (I), using one or more of the following methods.

1. By reaction of a compound of formula (II) with a compound of formula R¹ X, wherein R¹ is as defined for formula (I), and X is a suitable leaving group, e.g. halo (preferably chloro, bromo or iodo), C₁ -C₄ alkanesulphonyloxy, trifluoromethanesulphonyloxy or arylsulphonyloxy (preferably benzenesulphonyloxy or p-toluenesulphonyloxy), in the presence of an appropriate base, e.g. sodium or potassium carbonate or bicarbonate, or triethylamine, in a suitable solvent such as a C₁ -C₄ alkanol, 1,2-dimethoxyethane, acetonitrile, dimethylformamide or N,N-dimethylacetamide, and optionally in the presence of sodium or potassium iodide. The reaction can be conducted at from about 0° C. to about 150° C., preferably at from about room temperature to about 100° C.

2. By reductive alkylation of a compound of formula (II) using the appropriate aldehyde-, ketone- or carboxylic acid-containing R¹ precursor. In the case of an aldehyde or ketone precursor, the substrate (II) and carbonyl reagent may be reacted together under conventional catalytic hydrogenation conditions or in the presence of sodium cyanoborohydride, in a suitable solvent such as methanol or ethanol, at about room temperature. Alternatively, the reductive alkylation may be achieved by a two-step procedure in which the intermediate enamine is formed initially under conventional conditions and subsequently reduced to the required amine, e.g. using sodium cyanoborohydride in tetrahydrofuran-methanol at about room temperature.

In the case of a carboxylic acid precursor, the substrate (II) and the said acid reagent may be reacted together in the presence of excess sodium borohydride in a suitable solvent; preferably the carboxylic acid itself is used as solvent whenever possible. Since this reductive alkylation proceeds via in situ formation of the corresponding sodium triacyloxyborohydride, obvious variations are to employ preformed intermediate when commercially available or to preform it in a separate in situ step using the stoichiometric amount of carboxylic acid in a suitable solvent. An example of the latter procedure involves the treatment of six equivalents of the carboxylic acid with two equivalents of sodium borohyride in dry tetrahydrofuran at about room temperature. When formation of the required sodium triacyloxyborohydride is complete, the reaction mixture is treated with a solution of one equivalent of the substrate (II) in the same solvent and the subsequent reaction step is conducted at from about room temperature to about 70° C., preferably 50°-55° C.

3. When R¹ is C₂ -C₄ alkyl or C₃ -C₇ cycloalkyl, each substituted at the 2-position with a hydroxy group, by reaction of a compound of formula (II) with the appropriate epoxide-containing R¹ precursor, optionally in the presence of a tertiary amine base, e.g. triethylamine, and preferably in a suitable solvent such as C₁ -C₄ alkanol. The reaction can be conducted at from about 0° C. to about 150° C., preferably at from about room temperature to about 60° C.

When R¹ is 2-hydroxyethyl, an "ethylene oxide equivalent" is preferably employed. Thus a compound of formula (II) may be reacted with ethylene carbonate in a suitable solvent such as dimethylformamide at about 120° C.

4. When R¹ is C₂ -C₄ alkyl substituted at the 2-position with an electron withdrawing group such as R³ CO, R⁴ O₂ C, R⁵ R⁶ NOC, R⁵ R⁶ NO₂ S, R³ SO, R³ SO₂ and certain aryl and heteroaryl systems (e.g. 2- or 4-pyridyl), by conjugate addition (Michael-type reaction) of a compound of formula (II) to the corresponding α,β-unsaturated ketone-, ester-, amide-, sulphonamide-, sulphoxide-, sulphone-, arene- or heteroarene-containing R¹ precursor respectively, wherein R³, R⁴, R⁵ and R⁶ are as defined for formula (I), optionally in the presence of a tertiary amine base such as triethylamine. The reaction may optionally be conducted in a suitable solvent, e.g. N,N-dimethylacetamide, at from about 0° C. to about 100° C., preferably at about 100° C.

5. Certain compounds of formula (I) can be prepared from other compounds of formula (I) by, for example, the following conventional functional group transformations within the R¹ substituent:

(a) a compound of formula (I) wherein R¹ contains a R⁵ R⁶ NOC substituent is obtainable from a corresponding ester of formula (I), i.e. wherein R¹ contains a R⁴ O₂ C substituent, by direct amination using an amine of formula R⁵ R⁶ NH. The reaction is preferably carried out using an excess of the amine in a suitable solvent such as a C₁ -C₄ alkanol at an elevated temperature, e.g. the reflux temperature of the reaction medium. For low boiling amines, the reaction is preferably conducted in a sealed vessel.

The same over-all transformation can be effected indirectly via the intermediacy of the corresponding carboxylic acid, i.e. a compound of formula (I) wherein R¹ contains a HO₂ C substituent. Depending on the nature of the ester, its deprotection may be achieved by acid or alkaline hydrolysis, protonolysis (e.g. when R⁴ is t-butyl) or hydrogenolysis (e.g. when R⁴ is benzyl). Conversion of the acid to the required amide may also be achieved by a variety of methods. For example, the acid may be activated by formation of the corresponding acyl halide, e.g. bromide or chloride, followed by reaction of the latter with an amine of formula R⁵ R⁶ NH optionally in the presence of a reaction-inert base to act as acid scavenger. Alternatively, any of a host of standard amide bond-forming (peptide coupling) reagents may be used. For example, the acid may be activated using a carbodiimide such as 1-ethyl-3-dimethylaminopropylcarbodiimide, optionally in the presence of 1-hydroxybenzotriazole and a reaction-inert amine such as N-methylmorpholine, followed by in situ reaction of the activated acid with an amine of formula R⁵ R⁶ NH;

(b) a compound of formula (I) wherein R¹ contains a R³ SO or R³ SO₂ substituent is obtainable from the corresponding sulphide of formula (I), i.e. wherein R¹ contains a R³ S substituent, either by controlled oxidation using a stoichiometric amount of oxidising agent, or by using the required excess of oxidising agent, respectively. Suitable oxidising agents are, for example, a peracid such as meta-chloroperbenzoic acid, hydrogen peroxide or nitronium tetrafluoroborate.

Certain compounds of formula (I) are preparable from other compounds of formula (I) by conventional functional group transformations within the R² substituent also. For example, the procedures outlined in 5(b) above for R¹ may be applied to R², such that R¹⁰ S may be converted into either R¹⁰ SO or R¹⁰ SO₂.

Other possibilities are as follows:

(c) a compound of formula (I) wherein R² is, or contains, a H₂ NOC substituent is obtainable from the corresponding nitrile of formula (I), i.e. wherein R² is, or contains, a NC substituent, by controlled hydrolysis, e.g. using sulphuric acid, boron trifluoride or potassium hydroxide, or via a corresponding imino ether derivative.

(d) a compound of formula (I) wherein R² is, or contains, a R¹⁰ SO₂ N(R¹¹), R⁸ R⁹ NOCN(R¹¹) or R¹⁰ O₂ CN(R¹¹) substituent is obtainable from the corresponding amide of formula (I), i.e. wherein R² is, or contains, a R¹² CON(R¹¹) substituent. This may be achieved by hydrolysis of the amide to the corresponding amine using standard conditions, followed by reaction of the latter with, respectively, (i) a sulphonyl halide (preferably chloride) of formula R¹⁰ SO₂ halo or a sulphonic anhydride of formula (R¹⁰ SO₂)₂ O, or (ii) a carbamoyl chloride of formula ClCONR⁸ R⁹ or, when R⁸ is H, an isocyanate of formula R⁹ NCO or, when both R⁸ and R⁹ are H, an inorganic isocyanate such as potassium isocyanate in the presence of an acid, e.g. acetic acid, or (iii) a chloroformate of formula ClCO₂ R¹⁰. The sulphonylations, and the acylations not involving an isocyanate, are optionally carried out in the presence of a reaction-inert base to act as acid scavenger.

(e) a compound of formula (I) wherein R² is R¹³ CH₂ CH₂ may be obtained from the corresponding alkene of formula (I) wherein R² is R¹³ (CH₂)_(n) CH═CH, wherein n=0, by conventional catalytic or catalytic transfer hydrogenation, preferably using palladium as catalyst and, in the latter process, ammonium formate as the hydrogen source.

A compound of formula (II) may be obtained from a compound of formula (III): ##STR5## wherein R² and k are as previously defined for formula (II) and R¹⁴ forms part of a conventional amino acid N-protecting group, i.e. a carbamate, wherein R¹⁴ is preferably benzyl or t-butyl. N-Deprotection of a compound of formula (III) can be achieved using standard methodology; for example, when R¹⁴ is benzyl, by palladium-catalysed hydrogenolysis and, when R¹⁴ is t-butyl, by protonolysis using trifluoroacetic acid or hydrogen chloride.

Alternatively, when R¹⁴ is benzyl, N-deprotection can be effected by modification of the procedure reported in Tetrahedron Letters, 1988, 29, 2983, in which (III) is treated with an excess of a tri(lower alkyl)silane in the presence of a palladium(II) salt and an excess of a tri(lower alkyl)amine in a suitable solvent such as a C₁ -C₄ alkanol. Preferably the reaction is conducted using triethylsilane, palladium(II) acetate and triethylamine in ethanol at about room temperature.

Further useful non-hydrogenolytic N-deprotection procedures, when R¹⁴ is benzyl, are either to employ hydrogen bromide in glacial acetic acid at about 0° C. or a Lewis acid-catalysed nucleophilic deprotection using, for example, boron trifluoride etherate and excess ethanethiol in a suitable solvent such as dichloromethane at about room temperature.

Depending on the nature of R², a compound of formula (III) can be obtained by a variety of synthetic methods.

1. For example, when R² is an ethyl group substituted at the 2-position with R⁸ R⁹ NOC, R⁸ R⁹ NO₂ S, R¹⁰ S(O)_(m), R¹² CON(R¹¹), R₁₀ SO₂ N(R¹¹), R⁸ R⁹ NOCN(R¹¹) or R¹⁰ O₂ CN(R¹¹), i.e. a compound of formula (III) wherein R² is CH₂ CH₂ R¹³, wherein R¹³ and m are as previously defined for formula (I), and R¹⁴ and k are as previously defined for formula (III), by reduction of a compound of formula (IV): ##STR6## wherein R¹³ is as previously defined for formula (I), and R¹⁴ and k are as previously defined for formula (III). This may be achieved by conventional catalytic or catalytic transfer hydrogenation, preferably using palladium as catalyst and, in the latter case, ammonium formate as the hydrogen source.

Clearly, when R¹⁴ is benzyl, a compound of formula (IV) may be converted directly to a compound of formula (II) wherein R² is CH₂ CH₂ R¹³ under these conditions. Alternatively, when R¹⁴ is t-butyl, a compound of formula (IV) may be converted to a compound of formula (II) wherein R² is CH═CHR¹³ using the protonolysis conditions previously mentioned.

A compound of formula (IV) may be obtained from a compound of formula (V): ##STR7## wherein Y is chloro, bromo or iodo (preferably bromo), and R¹⁴ and k are as previously defined for formula (IV), with an alkene of formula CH₂ ═CHR¹³, wherein R¹³ is as previously defined for formula (IV), using the Heck reaction. Thus the desired coupling is achieved using, for example, an excess of the required alkene, in the presence of palladium(II) acetate, tri-o-tolylphosphine and triethylamine, in a suitable solvent such as acetonitrile or dimethylformamide, at from about 80° C. to about 160° C.

A compound of formula (V) may be obtained from a compound of formula (VI): ##STR8## wherein R¹⁴, k and Y are as previously defined for formula (V), by selective and exhaustive reduction of the ketonic carbonyl group. This may be achieved using an alkali metal borohydride salt, preferably lithium borohydride, in a suitable solvent such as tetrahydrofuran, at from about room temperature to about 70° C.

A compound of formula (VI) may be obtained by acylating a suitably activated derivative of a compound of formula (VII): ##STR9## wherein Y is as previously defined for formula (VI), with a suitably activated derivative of a compound of formula (VIII): ##STR10## wherein R¹⁴ and k are as previously defined for formula (VI). Thus the N-protected α-amino acid of formula (VIII) is converted to the corresponding acyl bromide or chloride, preferably chloride, by standard methodology, e.g. using oxalyl chloride, optionally in the presence of a catalytic amount of dimethylformamide, in a suitable solvent such as dry dichloromethane; the indole of formula (VII) is converted to the corresponding 1-magnesium halide derivative by treatment with a C₁ -C₄ alkyl magnesium halide, wherein halide means chloride, bromide or iodide, e.g. ethyl magnesium bromide, in a suitable solvent such as dry ether. The former acyl halide is then reacted with the latter 1-indolyl magnesium halide in a suitable solvent such as dry ether at from about -30° C. to about room temperature.

2. When R², R¹⁴ and k are as previously defined for formula (III), the said compounds of formula (III) may be prepared by transition metal catalysed cyclisation of a compound of formula (IX): ##STR11## wherein R¹⁵ is OR¹⁴, C₁ -C₄ alkyl, trifluoromethyl or phenyl, preferably trifluoromethyl, Z is chloro, bromo or iodo, preferably bromo or iodo, and R², R¹⁴ and k are as previously defined for formula (III). For example, the reaction is conducted in the presence of an appropriate transition metal catalyst, e.g. palladium(II) acetate or tris(triphenylphosphine)rhodium(I) chloride, a phase transfer catalyst, e.g. a tetra(C₁ -C₄)alkylammonium halide, and a base, e.g. a tertiary amine such as triethylamine, in a suitable solvent such as dimethylformamide, at about 155° C.

A compound of formula (IX) may be obtained by the alkylation of a compound of formula (X): ##STR12## wherein R², R¹⁵ and Z are as previously defined for formula (IX), with a compound of formula (XI): ##STR13## wherein R¹⁴ and k are as previously defined for formula (IX), using the Mitsunobu coupling procedure, preferably with triphenylphosphine and diethyl azodicarboxylate as the required reagents, in a suitable solvent such as tetrahydrofuran at about room temperature.

A compound of formula (X) may be obtained by standard acylation of an amine of formula (XII): ##STR14## wherein R² and Z are as previously defined for formula (X), with a chloroformate of formula R¹⁵ COCl or an acyl halide (preferably chloride) of formula R¹⁵ COhalo, wherein R¹⁵ is as previously defined for formula (X), or with an acid anhydride of formula (R¹⁵ CO)₂ O wherein R¹⁵ is as previously defined for formula (X) but is not OR¹⁴.

A compound of formula (XI) may be obtained by selective reduction of the ester group of a compound of formula (XIII): ##STR15## wherein R¹⁶ is C₁ -C₄ alkyl or benzyl, and R¹⁴ and k are as previously defined for formula (XI), using, for example, diisobutylaluminiumhydride in a suitable solvent such as tetrahydrofuran at about -70° C.

A compound of formula (XIII) may be obtained by reacting an aldehyde of formula (XIV): ##STR16## wherein R¹⁴ and k are as previously defined or formula (XIII), either with a phosphonium salt of formula (XV) or with a phosphonate of formula (XVI): ##STR17## wherein R¹⁷ is C₁ -C₄ alkyl or phenyl, preferably methyl or ethyl, R¹⁶ is as previously defined for formula (XIII), and Y is as previously defined for formula (V), using standard Wittig or Wittig-Horner reaction conditions.

It will be appreciated by persons skilled in the art that, within the various processes described, the order of the synthetic steps employed may be varied and will depend inter alia on factors such as the nature of other functional groups present in a particular substrate, the availability of key intermediates, and the protecting group strategy to be adopted (if any). Clearly, such factors will also influence the choice of reagent for use in said synthetic steps.

For example, an alternative approach to a compound of formula (I) wherein R² is an ethyl group substituted at the 2-position with R⁸ R⁹ NOC, R⁸ R⁹ NO₂ S, R¹⁰ S(O)_(m), R¹² CON(R¹¹), R¹⁰ SO₂ N(R¹¹), R⁸ R⁹ NOCN(R¹¹) or R¹⁰ O₂ CN(R¹¹), i.e. a compound of formula (I) wherein R² is CH₂ CH₂ R¹³, wherein R¹³ is as previously defined for formula (I), and R¹ and k are also as previously defined for formula (I), involves the reaction of a compound of formula (I) wherein R² is Y, wherein Y is as previously defined for formula (V), and R¹ and k are as previously defined for formula (I), with an alkene of formula CH₂ ═CHR¹³ wherein R¹³ is as defined above, under the Heck reaction conditions previously described for the conversion of (V) to (IV), optionally followed by hydrogenation of the product as in the conversion of (IV) to (III).

A compound of formula (I) wherein R² is Y, wherein Y is as previously defined for formula (V), and R¹ and k are as previously defined for formula (I), may be obtained by selective N-alkylation of a compound of formula (II) wherein R² is Y, wherein Y is as previously defined for formula (V), and k is as previously defined for formula (I), by analogy with the procedures described earlier for the conversion of (II) to (I).

A compound of formula (II) wherein R² is Y, wherein Y is as previously defined for formula (V), and k is as previously defined for formula (I), may be obtained from a compound of formula (V) wherein R¹⁴, k and Y are as previously defined for formula (V) by the standard N-deprotection methodology already described for the conversion of (III) to (II). Preferably however, when R¹⁴ is benzyl, deprotection is effected by a non-hydrogenolytic procedure.

Compounds of formulae (VII), (VIII), (XII), (XIV), (XV) and (XVI), and the various reagents required for the processes hereinbefore disclosed, when neither commercially available nor subsequently described, can be obtained either by analogy with the reactions described in the Examples and Preparations sections or by conventional synthetic procedures, in accordance with standard textbooks on organic chemistry or literature precedent, from readily accessible starting materials using appropriate reagents and reaction conditions. Clearly, when the preferred stereoisomers of formula (IA) are required, the compounds of formulae (VIII) and (XIV) will possess the 2R-configuration.

Persons skilled in the art will recognise that the alkenes depicted hereinbefore may be obtained in cisor trans-stereoisomeric forms, or as mixtures of cis- and trans-stereoisomers, and are represented in one such form only in the interests of clarity and convenience. Such persons will also be aware of variations of, and alternativesto, those reactions described hereinafter for the preparation of compounds of formula (I).

The pharmaceutically acceptable acid addition salts of compounds of formula (I) may also be prepared in a conventional manner. For example a solution of the free base is treated with the appropriate acid, either neat or in an appropriate solvent, and the resulting salt isolated either by filtration or by evaporation under vacuum of the reaction solvent. Certain such salts may be formed or interconverted using ion-exchange resin techniques.

The compounds of the invention are selective agonists at the "5-HT₁ -like" subtype of the 5-HT (serotonin) receptor and are therefore useful in the curative or prophylactic treatment of migraine and associated conditions such as cluster headache, chronic paroxysmal hemicrania and headache associated with vascular disorders. Certain of these compounds are also agonists at central 5-HT₁ receptors and are therefore useful for the treatment of depression, anxiety, eating disorders, obesity and drug abuse.

The in vitro evaluation of the "5-HT₁ -like" receptor agonist activity of the compounds of the invention is carried out by testing the extent to which they mimic sumatriptan in contracting the isolated dog saphenous vein strip (P. P. A. Humphrey et al., Brit. J. Pharmacol., 1988, 94, 1123). This effect can be blocked by methiothepin, a known 5-HT antagonist. Sumatriptan is known to be useful in the treatment of migraine and produces a selective increase in carotid vascular resistance in the anaesthetized dog and a consequent decrease in carotid arterial blood flow. It has been suggested (W. Feniuk et al., Brit. J. Pharmacol., 1989, 96, 83) that this is the basis of its efficacy.

The 5-HT₁ agonist activity of the compounds of the invention can be measured in in vitro receptor binding assays as described for the 5-HT_(1A) receptor, using rat cortex as the receptor source and [³ H]8-OH-DPAT as the radioligand (D. Hoyer et al., Europ. J. Pharmacol., 1985, 118, 13), and as described for the 5-HT_(1D) receptor, using bovine caudate as the receptor source and [³ H]5-HT as the radioligand (R. E. Heuring and S. J. Peroutka, J. Neuroscience, 1987, 7, 894).

In therapy, the compounds of formula (I) and their pharmaceutically acceptable salts can be administered alone, but will generally be administered in admixture with a pharmaceutical carrier selected with regard to the intended route of administration and standard pharmaceutical practice. For example, they can be administered orally in the form of tablets containing such excipients as starch or lactose, or in capsules or ovules either alone or in admixture with excipients, or in the form of elixirs, solutions or suspensions containing flavouring or colouring agents. They can also be injected parenterally, for example, intravenously, intramuscularly or subcutaneously. For parenteral administration, they are best used in the form of a sterile aqueous solution which may contain other substances, for example, enough salts or glucose to make the solution isotonic with blood. For buccal or sublingual administration they may be administered in the form of tablets or lozenges which can be formulated in a conventional manner.

For oral, parenteral, buccal and sublingual administration to patients, the daily dosage level of the compounds of formula (I) and their pharmaceutically acceptable salts will be from 0.01 to 20 mg/Kg (in single or divided doses). Thus tablets or capsules will contain from 5 mg to 0.5 g of active compound for administration singly, or two or more at a time, as appropriate. The physician in any event will determine the actual dosage which will be most suitable for an individual patient and it will vary with the age, weight and response of the particular patient. The above dosages are exemplary of the average case; there can, of course, be individual instances where higher or lower dosage ranges are merited, and such are within the scope of this invention.

Alternatively, the compounds of formula (I) and their pharmaceutically acceptable salts can be administered in the form of a suppository or pessary, or they may be applied topically in the form of a lotion, solution, cream, ointment or dusting powder. For example, they can be incorporated into a cream consisting of an aqueous emulsion or polyethylene glycols or liquid paraffin; or they can be incorporated, at a concentration of from 1 to 10%, into an ointment consisting of a white wax or white soft paraffin base together with such stabilisers and preservatives as may be required.

The compounds of formula (I) and their pharmaceutically acceptable salts can also be administered intranasally or by inhalation and are conveniently delivered in the form of a solution or suspension from a pump spray container, which is squeezed or pumped by the patient, or as an aerosol spray presentation from a pressurised container or a nebuliser with the use of a suitable propellant, e.g. dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas. In the case of a pressurised aerosol, the dosage unit may be determined by providing a valve to deliver a metered amount. The pressurised container or nebuliser may contain a solution or suspension of the active compound. Capsules and cartridges (made, for example, from gelatin) for use in an inhaler or insufflator may be formulated containing a powder mix of a compound of the invention and a suitable powder base such as lactose or starch.

Aerosol formulations are preferably arranged so that each metered dose or "puff" of aerosol contains from 20 μg to 1000 μg of a compound of formula (I), or a pharmaceutically acceptable salt thereof, for delivery to the patient. The overall daily dose with an aerosol will be within the range of from 100 μg to 10 mg which may be administered in a single dose or, more usually, in divided doses throughout the day.

Thus the invention provides pharmaceutical compositions comprising a compound of formula (I), or a pharmaceutically acceptable salt thereof, together with a pharmaceutically acceptable diluent or carrier.

The invention also provides a compound of formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity, for use in medicine.

The invention further includes the use of a compound of formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity, both for the manufacture of a medicament for the curative or prophylactic treatment of migraine or an associated condition such as cluster headache, chronic paroxysmal hemicrania or headache associated with a vascular disorder, or of depression, anxiety, an eating disorder, obesity or drug abuse, and also for the manufacture of a medicament for the curative or prophylactic treatment of a medical condition for which a selective agonist of 5-HT₁ -like receptors is indicated.

In a further aspect, the invention provides both a method of treating a human being to cure or prevent migraine or an associated condition such as cluster headache, chronic paroxysmal hemicrania or headache associated with a vascular disorder, or depression, anxiety, an eating disorder, obesity or drug abuse, and also a method of treating a human being to cure or prevent a medical condition for which a selective agonist of 5-TH₁ -like receptors is indicated, which comprises treating said human being with an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity.

The invention also includes any novel intermediates of formula (II) disclosed herein.

The syntheses of the compounds of the invention and of the intermediates for use therein are illustrated by the following Examples and Preparations. The purity of the compounds was routinely monitored by thin layer chromatography (Rf) using Merck Kieselgel 60 F₂₅₄ plates and the following solvent systems (SS):

1. dichloromethane;

2. dichloromethane:ethanol:0.880 aqueous ammonia, 90:10:1;

3. hexane:ethyl acetate, 1:1;

4. dichloromethane:methanol:0.880 aqueous ammonia, 90:10:1;

5. methanol;

6. ethyl acetate:diethylamine, 95:5;

7. dichloromethane:methanol:0.880 aqueous ammonia, 90:10:0.5.

¹ H Nuclear magnetic reasonance (NMR) spectra were recorded using either a Nicolet QE-300 or a Bruker AC-300 spectrometer and were in all cases consistent with the proposed structures- Chemical shifts (δ) are given in parts-per-million downfield from tetramethylsilane using conventional abbreviations for designation of major peaks: s, singlet; d, doublet; dd, doublet of doublets; t, triplet; m, multiplet; br, broad. LRMS means low resolution mass spectrum. Room temperature means 20°-25° C.

EXAMPLE 1

5-(2-Ethylsulphonylethyl)-3-[N-[2-pyridylmethyl)-2(R)-pyrrolidinylmethyl]-1H-indole

To a stirred solution of 5-(2-ethylsulphonylethyl)-3-(2(R)-pyrrolidinylmethyl)-1H-indole (Preparation 5; 150 mg, 0.47 mmol) in dry dimethylformamide (4 ml) at room temperature under nitrogen were added, sequentially, anhydrous sodium carbonate (110 mg, 1.04 mmol), 2-pyridylmethyl chloride hydrochloride (85 mg, 0.52 mmol) and sodium iodide (10 mg). The resulting mixture was heated at 100° C. for 18 hours, then allowed to cool to room temperature. It was then partitioned between ethyl acetate and water, and the organic phase separated, washed with water (3×), dried (Na₂ SO₄), and evaporated under reduced pressure to give an oil. Purification by column chromatography on silica gel, eluting with an ethanol in dichloromethane gradient (0 to 5% ethanol), afforded the title compound as a gum (62 mg). [α]_(D) ²⁵ +22° (c=0.1, CH₃ OH). Found: C,59.89; H,6.44; N,9.07. C₂₃ H₂₉ N₃ O₂ S; 0.75 CH₂ Cl₂ requires C,60.02; H,6.47; N,8.84%. δCDCl₃): 1.35(3H,t), 1.50-1.90(4H,m), 2.30-2.40(1H,m), 2.65-2.75(1H,m), 2.90(3H,q and m), 3.00-3.20(2H,m), 3.20-3.30(4H,m), 3.60(1H,d), 4.28(1H,d), 5.30(1.5H,s,CH₂ Cl₂), 7.02(1H,d), 7.05(1H,s), 7.16-7.20(1H,dd), 7.30(1H,d), 7.40(1H,s), 7.50(1H,d), 7.70(1H,dd), 8.14(1H,br s), 8.58(1H,d).

The following twenty seven compounds were obtained from Preparations 5, 6 or 7, employed either as the free base or hydrochloride salt, using an appropriate alkylating agent, the required amount of acid scavenger, and a suitable solvent such as dimethylformamide, N,N-dimethylacetamide or 1,2-dimethoxyethane, by procedures similar to that described in Example 1.

EXAMPLE 2

3-(N-Benzyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a gum, using preparation 5 and benzyl bromide- Rf 0.70 (SS 2). [α]_(D) ²⁵ +33° (c=0.1, CH₃ OH). Found: C,66.87; H,7.10; N,6.57. C₂₄ H₃₀ N₂ O₂ S; 0.125 H₂ O; 0.25 CH₂ Cl₂ requires C,67.10; H,7.14; N,6.45%. δ(CDCl₃): 1.35(3H,t), 1.50-1.90(4H,m), 2.25(1H,m), 2.65-3.40(9H,m), 2.90(2H,q), 4.15(1H,d), 5.30(0.5H,s,CH₂ Cl₂), 7.00(1H,d), 7.05(1H,s), 7.25-7.40(7H,m), 8.00(1H,br s).

EXAMPLE 3

3-(N-Allyl-2(R)-pyrroldinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a gum, using preparation 5 and allyl bromide. Rf 0.70 (SS 2). [α]_(D) ²⁵ +53° (c=0.1, CH₃ OH). Found: C, 63.98; H, 7.92; N, 7.48. C₂₀ H₂₈ N₂ O₂ S; 0.50 H₂ O; 0.125 CH₂ Cl₂ requires C,63.58; H,7.75; N,7.37%. δ(CDCl₃): 1.38(3H,t), 1.50-1.90(4H,m), 2.20-2.35(1H,m), 2.60-2.80(2H,m), 2.90-3.00(3H,m), 3.10-3.40(6H,m), 3.65(1H,dd), 5.15(1H,d), 5.25(1H,d), 5.30(0.25H,s, CH₂ Cl₂), 5.95-6.10(1H,m), 7.05(1H,d), 7.08(1H,s), 7.30(1H,d), 7.42(1H,s), 8.05(1H,br s).

EXAMPLE 4

5-(2-Ethylsulphonylethyl)-3-[N-(2-methoxyethyl)-2-(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a gum, using preparation 5 and 2-methoxyethyl bromide. Rf 0.35 (SS 2). [α]_(D) ²⁵ +49° (c=0.1, CH₃ OH). Found: C,58.81; H,7.45; N,6.58. C₂₀ H₃₀ N₂ O₃ S; 0.50 CH₂ Cl₂ requires C,58.48; H,7.42; N,6.65%. δ(CDCl₃): 1.38(3H,t), 1.50-1.90(4H,m), 2.20-2.35(1H,m), 2.45-2.55(1H,m), 2.60-2.80(2H,m), 2.92(2H,q), 3.10-3.35(7H,m), 3.40(3H,s), 3.65-3.70(2H,m), 5.30(1H,s,CH₂ Cl₂), 7.04(1H,d), 7.08(1H,s), 7.30(1H,d), 7.45(1H,s), 8.05(1H,br s).

EXAMPLE 5

5-(2-Ethylsulphonylethyl)-3-[N-(2-oxopropyl)-2(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a gum, using Preparation 5 and chloroacetone. Rf 0.60 (SS 4). [α]_(D) ²⁵ +28.sup.° (c=0.1, CH₃ OH). Found: C,62.41; H,7.40; N,7.20. C₂₀ H₂₈ N₂ O₃ S; 0.10 CH₂ Cl₂ requires C,62.70; H,7.38; N,7.28%. δ(CDCl₃): 1.38(3H,t), 1.50-1.90(4H,m), 2.15(3H,s), 2.20-2.30(1H,m), 2.68-2.75(1H,m), 2.80-3.08(5H,m), 3.15(1H,d), 3.20-3.38(4H,m), 3.68(1H,d), 5.30(0.20H,s,CH₂ Cl₂), 7.02(2H,m), 7.30(1H,d), 7.42(1H,s), 8.00(1H,br s).

EXAMPLE 6

3-(N-Cinnamyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a foam, using Preparation 5 and cinnamyl bromide. Rf 0.80 (SS 4). [α]_(D) ²⁵ -27° (c=0.1, CH₃ OH). Found: C,63.73; H,6.66; N,5.78. C₂₆ H₃₂ N₂ O₂ S; H₂ O; 0.50 CH₂ Cl₂ requires C,64.02; H,6.49; N,5.64%. δ(CDCl₃): 1.30(3H,t), 1.70-2.08(4H,m), 2.60(1H,m), 2.84-2.95(3H,m), 3.10-3.50(8H,m); 3.68(1H,dd), 5.30(1H,s,CH₂ Cl₂), 6.28-6.38(1H,m), 6.48(1H,d), 7.00(1H,d), 7.18-7.35(7H,m), 7.42(1H,s), 8.62(1H,br s).

EXAMPLE 7

3-[N-(3-Cyclohexenyl)-2(R)-pyrrolidinylmethyl]-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a foam, using Preparation 5 and 3-bromocyclohexene. Rf 0.70 (SS 4). [α]_(D) ²⁵ +3° (c=0.1, CH₃ OH). Found: C,64.33; H,7.51; N,6.76. C₂₃ H₃₂ N₂ O₂ S; 0.25 H₂ O; 0.33 CH₂ Cl₂ requires C,64.66; H,7.71; N,6.46. δ(CDCl₃): 1.38(3H,t), 1.50-2.30(11H,m), 2.80-3.00(3H,m), 3.10-3.60(7H,m), 3.70-3.84(1H,m), 5.30(0.67H,s,CH₂ Cl₂), 5.68-6.10(2H,m), 7.05(1H,d), 7.20(1H,br s), 7.34(1H,d), 7.42(1H,s), 8.22(1H,br s).

EXAMPLE 8

5-(2-Ethylsulphonylethyl)-3-[N-(3-methyl-2-butenyl)-2(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a gum, using Preparation 5 and 3-methyl-2-butenyl bromide. Rf 0.55 (SS 4). [α]_(D) ²⁵ +36° (c=0.1, CH₃ OH). Found: C,64.72; H,8.05; N,6.91. C₂₂ H₃₂ N₂ O₂ S; 0.50 H20; 0.14 CH₂ Cl₂ requires C,64.91; H,8.19; N,6.84. δ(CDCl₃): 1.38(3H,t), 1.50-1.90(10H,m), 2.30(1H,m), 2.75(1H,m), 2.90-3.02(4H,m), 3.10-3.35(6H,m), 3.55(1H,m), 5.38(1H, br t), 7.00-7.10(2H,m), 7.30(1H,d), 7.42(1H,s), 8.00(1H, br s).

EXAMPLE 9

3-(N-Cyclopentyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a foam, using Preparation 5 and cyclopentyl iodide. Rf 0.36 (SS 4). [α]_(D) ²⁵ +29° (c=0.1, CH₃ OH). Found: C,64.28; H,7.80; N,6.40. C₂₂ H₃₂ N₂ O₂ S; 0.80 H₂ O; 0.10 CH₂ Cl₂ requires C,64.49; H,8.27; N,6.81%. δ(CDCI₃): 1.38(3H,t), 1.50-2.10(12H,m), 2.60-2.90(2H,m), 2.90(2H,q), 3.10-3.50(8H,m), 5.30(0.20H,s,CH₂ Cl₂), 7.04(1H,d), 7.10(1H,s), 7.32(1H,d), 7.40(1H,s), 8.18(1H,br s).

EXAMPLE 10

3-(N-Cyclopropylmethyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a foam, using Preparation 5 and cyclopropylmethyl bromide. Rf 0.44 (SS 4). [α]_(d) ²⁵ +47° (c=0.1, CH₃ OH). Found: C,65.05; H,8.27; N,7.27. C₂₁ H₃₀ N₂ O₂ S; 0.40 H₂ O; 0.05 CH₂ Cl₂ requires C,65.34; H,8.05; N,7.24%. δ(CDCl₃): 0.22(2H,m), 0.60(2H,m), 1.05(1H,m), 1.38(3H,t), 1.96-2.55(4H,m), 2.10(1H,m), 2.38(1H,m), 2.78 (1H,m), 2.90-3.05(4H,m), 3.15-3.35 (5H,m), 3.52(1H,m), 5.30 (0.10H, s, CH₂ Cl₂), 7.04(1H,d), 7.10 (1H,br s), 7.30(1H,d), 7.40(1H,s), 8.05 (1H, br s).

EXAMPLE 11

3-(N-Carbamoylmethyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethyl-1H-indole

Obtained as a foam, using preparation 5 and 2-bromoacetamide. Rf 0.50 (SS 4). [α]_(D) ²⁵ +25° (c=0.1, CH₃ OH). Found: C,58.94; H,6.81; N,10.70. C₁₉ H₂₇ N₃ O₃ S; 0.17 CHIC12 requires C,58.77; H,7.03; N,10.73%. (CDCl₃): 1.40(3H,t), 1.50-1.95(5H,m), 2.35(1H,m), 2.70(1H,m), 2.85-3.00(4H,m), 3.10-3.35(5H,m), 3.42(1H,d), 5.30(0.33H,s,CH₂ Cl₂), 5.55(1H,br s), 6.98(1H,s), 7.04(1H,d), 7.10(1H,br s), 7.30(1H,d), 7.60(1H,s), 8.10(1H, br s).

EXAMPLE 12

5-(2-Ethylsulphonylethyl)-3-[N-(4-pyridylmethyl)-2(R)-pyrroldinylmethyl]-1H-indole

Obtained as a gum, using preparation 5 and 4-pyridylmethyl chloride hydrochloride. Rf 0.75 (SS 4). [α]_(D) ²⁵ +13° (c=0.1,CH₃ OH). Found: C,59.60; H,6.45; N,9.00. C₂₃ H₂₉ N₃ O₂ S; 0.80 CH₂ Cl₂ requires C,59.61; H,6.43; N, 8.76%. δ(CDCl₃): 1.35(3H,t), 1.55-1.92(5H,m), 2.20(1H,m), 2.70-3.25(5H,m), 3.28(4H,s), 3.35(1H,d), 4.15(1H,d), 5.30(1.60H,s,CH₂ Cl₂), 7.12-7.18(2H,m), 7.32(3H,m), 7.40(1H,s), 8.15(1H,br s), 8.55(2H,d).

EXAMPLE 13

5-(2-Ethylsulphonylethyl)-3-{N-(1(R,S)-phenylethyl]-2(R)-pyrrolidinylmethyl}-1H-indole

Obtained as a foam, using Preparation 5 and α-methylbenzyl bromide. Rf 0.80 and 0.90 (SS 4), 0.30 and 0.40 (SS 5). [α]_(D) ²⁵ -14° (c=0.1, CH₃ OH). Found: C,69.15; H,7.44; N,6.42. C₂₅ H₃₂ N₂ O₂ S; 0.50 H₂ O requires C,69.25; H,7.67; N,6.46%. δ(CDCl₃)--1:1 mixture of diastereoisomers: 1.30-2.00(10H,m), 2.40-2.90(3H,m), 2.90(2H, 2xq), 3.05-3.40(6H,m), 3.65 and 4.04(1H,m), 6.80-7.00(2H,m), 7.10-7.60(7H,m), 7.96 and 8.02(1H, br s).

EXAMPLES 13A AND 13B

5-(2-Ethylsulphonylethyl)-3-{N-[(R)-phenylethyl]-2(R)-pyrrolidinylmethyl}-1H-indole and

5-(2-Ethylsulphonylethyl)-3-{N-[1(S)-phenylethyl]-2(R)-pyrrolidinylmethyl}-1H-indole

The mixture of diastereoisomers of Example 13 was resolved by conventional column chromatography on silica gel to afford the title compounds as diastereoisomer 1 and diastereoisomer 2. However, which diastereoisomer corresponds with which title compound was not established.

Diastereoisomer 1

Obtained as a foam. Rf 0.40 (SS 5). [α]_(D) ²⁵ +33° (c=0.1, C₃ OH). Found: C,69.60; H,7.40; N,6.85. C₂₅ H₃₂ N₂ O₂ S; 0.33 H₂ O requires C,69.73; H,7.64; N,6.51%. δ(CDCl₃): 1.38(3H,t), 1.50-1.90(7H,m), 2.50-3.00(5H, q and m), 3.05-3.31(6H,m), 4.06(1H,m), 6.84-7.10(2H,m), 7.30(1H,m), 7.42(6H,m), 7.98(1H,br s).

Diastereoisomer 2

Obtained as a foam. Rf 0.30 (SS 5). [D]_(D) ²⁵ -53° (c=0.1, CH₃ OH). Found: C,69.63; H,7.70; N,6.34. C₂₅ H₃₂ N₂ O₂ S; 0.33 H₂ O requires C,69.73; H,7.64; N,6.51%. δ(CDCl₃): 1.30-1.90(10H, t and m), 2.30-3.00(5H, q and m), 3.10-3.20(6H,m), 3.68(1H,m), 6.90(1H,s), 6.95(1H,d), 7.25(1H,m), 7.30-7.60(6H,m), 7.90(1H, br s).

EXAMPLE 14

5-(2-Ethylsulphonylethyl)-3-[N-(2-phenylethyl)-2(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a foam, using Preparation 5 and 2-phenylethyl iodide. Rf 0.83 (SS 4). [α]_(D) ²⁵ +33° (c=0.1, CH₃ OH). Found: C,68.39; H,7.55; N,6.30. C₂₅ H₃₂ N₂ O₂ S; 0.20 CH₂ Cl₂ requires C,68.54; H,7.40; N,6.34% δ(CDCl₃): 1.40(3H,t), 1.60-2.00(5H,m), 2.45(1H,m), 2.60(1H,m), 2.70-2.98(5H,m), 3.15-3.34(6H,m), 3.45(1H,m), 5.30(0.40H,s,CH₂ Cl₂), 7.05-7.10(2H,m), 7.15-7.36(6H,m), 7.45(1H,s), 8.08(1H,br s).

EXAMPLE 15

3-(N-Benzyloxycarbonylmethyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a gum, using Preparation 5 and benzyl bromoacetate. Rf 0.80 (SS 4). [α]_(D) ²⁵ +30° (c=0.1, CH₃ OH). Found: C,66.01; H,6.82; N,5.74. C₂₆ H₃₂ N₂ O₄ S; 0.25 H₂ O requires C,66.00; H,6.92; N,5.92%. δ(CDCl₃): 1.36(3H,t), 1.44-2.04(5H,m), 2.64(1H,m), 2.80(1H,m), 2.92(2H,q), 3.02-3.44(7H,m), 3.70(1H,d), 5.10(2H,q), 7.03(1H,d), 7.10(1H,br s), 7.22-7.40(6H,m), 7.42(1H,s), 7.94 (1H,br s).

EXAMPLES 16A AND 16B

3-{N-[1(R)-Carbamoylethyl]-2(R)-pyrrolidinylmethyl}-5-(2-ethylsulphonylethyl)-1H-indole and

3-{N-[1(S)-Carbamoylethyl]-2(R)-pyrrolidinylmethyl}-5-(2-ethylsulphonylethyl)-1H-indole

The mixture of diastereoisomers obtained using Preparation 5 and 2-bromopropionamide was resolved by conventional column chromatography on silica gel to afford the title compounds as diastereoisomer 1 and diastereoisomer 2. However, which diastereoisomer corresponds with which title compound was not established.

Diastereoisomer 1

Obtained as a foam. Rf 0.55 (SS 4). [α]_(D) ²⁵ +24° (c=0.1, CH₃ OH). Found: C,59.56; H,7.42; N,10.18. C₂₀ H₂₉ N₃ O₃ S; 0.25 H₂ O; 0.10 CH₂ Cl₂ requires C,59.68; H,7.40; N,10.39%. δ(CDCl₃): 1.24(3H,d), 1.35(3H,t), 1.52-1.90(4H,m), 2.58-2.72(2H,m), 2.82(1H,m), 2.85-3.10(4H,m), 3.15-3.35(4H,m), 3.50(1H,q), 5.30(0.20H, CH₂ Cl₂), 5.65(1H,br s), 7.00-7.08(2H,m), 7.20(1H,br s), 7.28(1H,d), 7.40(1H,s), 8.30(1H,br s).

Diastereoisomer 2

Obtained as a foam. Rf 0.50(SS 4). [α]_(D) ²⁵ +26° (c=0.1, CH₃ OH). Found: C,59.25; H,7.20; N,10.11C₂₀ H₂₉ N₃ O₃ S; 0.25 CH₂ Cl₂ requires C,58.92; H,7.20; N,10.18%. δ(CDCl₃): 1.35-1.40(6H,d and t), 1.56-1.85(4H,m), 2.56(1H,m), 2.70(1H,m), 2.86-3.00(3H,m), 3.10(1H,m), 3.22-3.35(5H,m), 3.40(1H,q), 5.30(0.50H,s,CH₂ Cl₂), 5.80(1H,br s), 6.85(1H,br s), 6.96-7.02(2H,m), 7.30(1H,d), 7.40(1H,d), 8.35(1H, br s).

EXAMPLE 17

5-(2-Ethylsulphonylethyl-3-[N-(3-methoxy-1-propyl)-2(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a foam, using preparation 5 and 3-methoxy-1-propyl bromide. Rf 0.47 (SS 4). [α]_(D) ²⁵ +58° (C=0.1, CH₃ OH). Found: C,62.78; H,8.25; N,6.99. C₂₁ H₃₂ N₂ O₃ S; 0.125 CH₂ Cl₂ requires C, 62.92; H, 8.06; N,6.95%. δ(CDCl₃): 1.40(3H,t), 1.55-1.95(6H,m), 2.24-2.45(2H,m), 2.65-2.85(2H,m), 2.96(2H,q), 3.08-3.38(10H,m), 3.50(2H,m), 5.30(0.25H,s,CH₂ Cl₂), 7.05(1H,d), 7.10(1H,s), 7.35(1H,d), 7.45(1H,s), 8.10 (1H,br s).

EXAMPLE 18

3-(N-Cyclobutylmethyl-2(R)-pyrolidinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

This compound was also prepared by an alternative procedure (b).

(a)

Obtained as a foam, using preparation 5 and cyclobutylmethylbromide. Rf 0.40 (SS 4). [α]_(D) ²⁵ +25° (c=0.1, CH₃ OH). Found: C,65.88; H,8.58; N,7.16. C₂₂ H₃₂ N₂ O₂ S; 0.10 CH₂ Cl₂ ; 0.30 H₂ O requires C,65.86; H,8.22; N,6.95%. δ(CDCl₃): 1.35(3H,t), 1.52-2.00(8H,m), 2.16-2.22(2H,m), 2.25-2.50(2H,m), 2.60-3.02(5H,m), 3.06-3.12(1H,m), 3.16-3.40(6H,m), 5.30(0.20H,s,CH₂ Cl₂), 7.02(1H,d), 7.10(1H,s), 7.32(1H,d), 7.44(1H,s), 8.35(1H,br s).

(b)

Sodium borohydride (76 mg, 2.0 mmol) was added in small portions to a stirred solution of cyclobutanecarboxylic acid (600 mg, 6.0 mmol) in dry tetrahydrofuran (10 ml) at room temperature under nitrogen- After 2.5 hours, when gas evolution had ceased, a solution of 5-(3-ethylsulphonylethyl)-3-(2(R)-pyrroldinylmethyl)-1H-indole (preparation 5; 320 mg, 1.0 mmol) in dry tetrahydrofuran (5 ml) was added and the resulting reaction mixture heated at 50°-55° C. for 2 days. The cool reaction mixture was then treated with 0.5M aqueous sodium hydroxide solution until basic and extracted with ethyl acetate. The combined extracts were washed with water (2×), dried (Na₂ SO₄) and evaporated under reduced pressure, then the resulting residue purified by column chromatography on silica gel, eluting with a gradient of ethanol in dichloromethane (0 to 10% ethanol), to provide the title compound as a foam (145 mg). Rf 0.40 (SS 4). Found: C,66.41; H,8.20; N,7.16. C₂₂ H₃₂ N₂ O₂ S; 0.15 CH₂ Cl₂ requires C,66.29; H,8.11; N, 6.97% δ(CDCl₃): 1.37(3H,t), 1.60-2.00(8H,m), 2.03-2.20(2H,m), 2.30-2.48(2H,m), 2.62-2.98(5H,m), 3.05-3.16(1H,m), 3.18-3.44(6H,m), 5.30(0.30 H,s,CH₂ Cl₂), 7.00(1H,d), 7.10(1H,s), 7.32(1H,d), 7.38(1H,s), 8.60(1H,br s).

EXAMPLE 19

3-[N-(2-Methoxyethyl)-2(R)-pyrrolidinylmethyl]-5-(2-phenylsulphonylethyl)-1H-indole

Obtained as a gum, using Preparation 6 and 2methoxyethyl bromide. Rf 0.60 (SS 4). [α]_(D) ²⁵ +23.sup.° (c=0.1, CH₃ OH). Found: C,67.58; H,6.90; N,6.61. C₂₄ H₃₀ N₂ O₃ S requires C,67.57; H,7.09; N,6.57%. δ(CDCl₃): 1.50-1.85(4H,m), 2.25(1H,m), 2.50(1H,m), 2.55-2.80(2H,m), 3.08-3.30(6H,m), 3.35-3.45(4H,m), 3.50-3.60(2H,m), 6.90(1H,d), 7.02(1H,br s), 7.24(1H,d), 7.30(1H,s), 7.56-7.68(3H,m), 7.90-8.00(3H,m).

EXAMPLE 20

3-[N-Cyclopropylmethyl-2(R)-pyrrolidinylmethyl)-5-(2-phenylsulphonylethyl)-1H-indole

Obtained as a foam, using Preparation 6 and cyclopropylmethyl bromide. Rf 0.54 (SS 4). [α]_(D) ²⁵ +5° (c=0.1, CH₃ OH). Found: C,67.54; H,7.13; N,6.26. C₂₅ H₃₀ N₂ O₂ S; H₂ O; 0.05 CH₂ Cl₂ requires C,67.63; H,7.27; N,6.30%. δ(CDCl₃): 0.28(2H,m), 0.65(2H,m), 1.14(1H,m), 1.70-2.15(4H,m), 2.30(1H,m), 2.62(1H,m), 2.80-3.12 (2H,m), 3.15-3.20(2H,m), 3.30-3.50(4H,m), 3.70(1H,m), 5.30(0.10H,s,CH₂ Cl₂), 6.94(1H,d), 7.20(1H,s), 7.28-7.34(2H,m), 7.60-7.75(3H,m), 8.00(2H,d), 8.20(1H,br s).

EXAMPLE 21

3-(N-Cyclopentyl-2(R)-pyrrolidinylmethyl)-5-(2-phenylsulphonylethyl)-1H-indole

Obtained as a foam, using preparation 6 and cyclopentyl iodide. Rf 0.52 (SS 4). [α]_(D) ²⁵ +105° (c=0.1, CH₃ OH). Found: C,66.95; H,7.25; N,6.27. C₂₆ H₃₂ N₂ O₂ S; 1.67 H₂ O requires C,66.91; H,7.63 ; N,6.00%. δ(CDCl₃): 1.50-2.20(12H,m), 2.80-3.05(3H,m) 3.10-3.20(3H,m), 3.30-3.60(6H,m), 6.94(1H,d), 7.10(1H,s), 7.28(1H,d), 7.55-7.70(3H,m), 7.96(1H,d), 8.35(1H,br s).

EXAMPLE 22

3-[N-(3-Methyl-2-butenyl)-2(R)-pyrrolidinylmethyl]-5-(2-phenylsulphonylethyl)-1H-indole

Obtained as a gum, using preparation 6 and 3-methyl-2-butenyl bromide. Rf 0.60 (SS 4). [α]_(D) ²⁵ +6° (c=0.1, CH₃ OH). Found: C,70.75; H,7.55; N,6.30. C₂₆ H₃₂ N₂ O₂ S; 0.10 CH₂ Cl₂ requires C,70.43; H,7.29; N,6.29%. δ(CDCl₃): 1.50-1.85(10H,m), 2.22(1H,m), 2.50-2.70(2H,m), 2.92(1H,m), 3.10-3.22(4H,m), 3.40-3.50 (3H,m), 5.30(0.20H,s,CH₂ Cl₁₂), 5.38(1H,m), 6.88(1H,d), 7.00(1H,s), 7.25(1H,d), 7.30(1H,s), 7.56-7.70(3H,m), 7.95-8.00(3H,m).

EXAMPLE 23

5-Bromo-3-(N-cyclopropylmethyl-2-(R)-pyrrolidinylmethyl)-1H-indole

Obtained as a foam, using preparation 7 and cyclopropylmethyl bromide. Rf 0.24 (SS 6). [α]_(D) ²⁵ +72° (c=0.1, CH₃ OH). Found: C,61.22; H,6.40; N,8.39. C₁₇ H₂₆ BrN₂ requires C, 61.26; H, 6.35; N,8.41%. δ(CDCl₃): 0.12-0.20(2H,m), 0.50-0.58(2H,m), 0.92-1.08(1H,m), 1.50-1-92 (4H,m), 1.98-2.08(1H,m), 2.20-2.30(1H,m), 2.55-2.68(2H,m), 2.90-2.98(1H,m), 3.08-3.18 (1H,m), 3.38-3.50(1H,m), 7.04(1H,s), 7.20-7.28 (2H,m), 7.70(1H,s), 8.10(1H,br s).

EXAMPLE 24

5-Bromo-3-[N-(2-methoxyethyl)-2-(R)-pyrrolidinylmethyl)-1H-indole

Obtained as an oil, using Preparation 7 and 2-methoxyethyl bromide. Rf 0.45 (SS 4). Found: C,57.25; H,6.41; N,8.14. C₁₆ H₂₁ Br N₂ O requires C,56.98; H,6.28; N,8.31%. δ(CDCl₃): 1.46-1.90(4H,m), 2.18-2.31(1H,m), 2.42-2.52(1H,m), 2.55-2.75(2H,m), 3.05-3.30(3H,m), 3.40(3H,s), 3.52-3.65(2H,m), 7.05(1H,s), 7.21-7.31(2H,m), 7.74(1H,s), 8.04(1H,br s).

EXAMPLE 25

5-Bromo-3-[N-(2-propyl)-2(R)-pyrrolidinylmethyl)-1H-indole

Obtained as a foam, using Preparation 7 and 2-iodopropane. Rf 0.24 (SS7). [α]_(D) ²⁵ +66° (c=0.1, CH₃ OH). Found: C,59.81; H,6.99; N,8.50. C₁₆ H₂₁ BrN₂ requires C,59.82; H,6.59; N,8.72%. δ(CDCl₃): 1.08(3H,d), 1.22(3H,d), 1.48-1.86(4H,m), 2.45-2.63(2H,m), 2.90-3.18(4H,m), 7.02(1H,s), 7.18-7.32(2H,s), 7.75(1H,s), 8.02(1H,br s).

EXAMPLE 26

5-(2-Ethylsulphonylethyl)-3-[N-(2-hydroxyethyl)-2(R)pyrrolidinylmethyl]-1H-indole

To a stirred solution of 5-(2-ethylsulphonylethyl)-3-(2(R)-pyrrolidinylmethyl)-1H-indole (Preparation 5; 350 mg, 1.1 mmol) in dry dimethylformamide (10 ml) at room temperature under nitrogen was added ethylene carbonate (160 mg, 1.8 mmol). The mixture was heated at 120° C. for 18 hours, allowed to cool, then partitioned between ethyl acetate and water. The organic phase was separated, washed with water (3×), dried (Na₂ SO₄) and evaporated under reduced pressure to give a foam. Purification by column chromatography on silica gel, eluting initially with dichloromethane followed by a gradient of 0.880 aqueous ammonia:ethanol: dichloromethane (0:10:90 to 0.5:10:90), afforded the title compound as gum. Rf 0.35 (SS 4). Found: C,62.29; H,7.73; N,7.23. C₁₉ H₂₈ N₂ O₃ S; 0.05 CH₂ Cl₂ requires C,62.04; H,7.68; N,7.60%. δ(CDCl₃): 1.35(3H,t), 1.50-1.90(5H,m), 2.30(1H,m), 2.50(1H,m), 2.70(1H,m), 2.80-3.35(10H,m), 3.60-3.75(2H,m), 5.30(0.10H,s,CH₂ Cl₂), 7.00(1H,d), 7.05(1H,s), 7.25(1H,d), 7.40(1H,s), 8.25(1H,br s).

EXAMPLE 27

5-(2-Ethylsulphonylethyl)-3-{N-[2(S)-hydroxy-1-propyl]-2(R)-pyrrolidinylmethyl}-1H-indole

To a stirred solution of 5-(2-ethylsulphonylethyl)-3-(2(R)-pyrrolidinylmethyl)-1H-indole hydrochloride (Preparation 5; 200 mg, 0.56 mmol) in methanol (2 ml) at room temperature under nitrogen was added triethylamine (0.09 ml). After 10 minutes, (S)-(-)-propylene oxide (0.05 ml, 0.71 mmol) and then water (12 ml) were added and the reaction mixture was warmed at 50° C. for 18 hours. The cool reaction mixture was evaporated under reduced pressure and the residue partitioned between ethyl acetate and water. The organic phase was separated, washed with water, dried (Na₂ SO₄) and evaporated under reduced pressure to give an oil. Purification by column chromatography on silica gel, eluting with a gradient of ethanol in dichloromethane (0 to 10% ethanol), afforded the title compound as a gum (48 mg). Rf 0.50 (SS 4). [α]_(D) ²⁵ +58° (c=0.1, CH₃ OH). Found: C,57.44; H,7.58; N,6.39. C₂₀ H₃₀ N₂ O₃ S; 0.50 H₂ O; 0.50 CH₂ Cl₂ requires C,57.26; H,7.50; N,6.52%. δ(CDCl₃): 1.15(3H,d), 1.38(3H,t), 1.50-1.90(4H,m), 2.20-2.38(2H,m), 2.60-2.75(2H,m), 2.85-2.95(3H,m), 3.10(1H,m), 3.20-3.38(5H,m), 3.60-3.90(2H,m), 5.30(1H,s,CH₂ Cl₂), 7.02(1H,d), 7.05(1H,s), 7.32(1H,d), 7.40(1H,s), 8.10(1H,br s).

The following two compounds were obtained from Preparation 5, either as the free base or hydrochloride salt, using the appropriate epoxide alkylating agent and required amount of triethylamine as acid scavenger, by procedures similar to that described in Example 27.

EXAMPLE 28

5-(2-Ethylsulphonylethyl)-3-{N-[2(R)-hydroxy-1-propyl]-2(R)-pyrrolidinylmethyl}-1H-indole

Obtained as a gum, using (R)-(+)-propylene oxide. Rf 0.50 (SS 4). [α]_(D) ²⁵ +36° (c=0.1, CH₃ OH). Found: C,59.92; H,7.80; N,6.97. C₂₀ H₃₀ N₂ O₃ S; 0.67 H₂ O; 0.17 CH₂ Cl₂ requires C,59.85; H,7.88; N,6.92%. δ(CDCl₃): 1.10(3H,d), 1.35(3H,t), 1.50-2.00(4H,m), 2.55(1H,m), 2.70-2.86(3H,m), 2.90(2H,q), 3.15-3.45(6H,m), 3.95(1H,m), 3.80-4.60(1H,br s), 5.30(0.33H,s,CH₂ Cl₂), 7.02(1H,d), 7.10(1H,s), 7.32(2H,d), 7.40(1H,s), 8.50(1H,br s).

EXAMPLE 29

5-(2-Ethylsulphonylethyl)-3-[N-(trans-2-hydroxycyclopenyl)-2(R)-2(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a gum, using cyclopentene oxide. Rf 0.30(SS 4). [α]_(D) ²⁵ +11° (c=0.1, CH₃ OH). Found: C,58.81; H,7.05; N,6.22. C₂₂ H₃₂ N₂ O₃ S; 0.50 H₂ O; 0.50 CH₂ Cl₂ requires C,59.25; H,7.51; N,6.14%. δ(CDCl₃)- 1:1 mixture of two pairs of diastereoisomers: 1.34 and 1.36 (3H, 2×t), 1.50-2.20(10H,m), 2.70-3.04(5H,m), 3.10-3.65(8H,m), 4.22-4.42(1H,m), 5.30(1H,s,CH₂ Cl₂), 6.98-7.05 and 7.18(2H,m and s), 7.30 and 7.32(1H, 2×d), 7.45 and 7.55(1H, 2×s), 8.50 and 8.55(1H, 2×s).

EXAMPLE 30

5-(2-Ethylsulphonylethyl)-3-[N-(2-methylsulphonylethyl)-2(R)-pyrrolidinylmethyl]-1H-indole

5-(2-Ethylsulphonylethyl)-3-(2(R)-pyrrolidinylmethyl)-1H-indole hydrochloride (Preparation 5; 200 mg, 0.56 mmol) was dissolved in N,N-dimethylacetamide (4 ml) under nitrogen at room temperature, then methyl vinyl sulphone (0.06 ml, 0.69 mmol) and triethylamine (0.2 ml) were added. The resulting mixture was heated at 100° C. for 18 hours, allowed to cool, then partitioned between ethyl acetate and water. The organic phase was separated, washed with water, dried (Na₂ SO₄) and evaporated under reduced pressure. The resulting crude material was purified by column chromatography on silica gel, eluting with a gradient of ethanol in dichloromethane (0 to 5% ethanol), to afford the title compound as a gum (130 mg). Rf 0.70 (SS 4). [α]_(D) ²⁵ +43° (c=0.1, CH₃ OH). Found: C,55.38; H,7.12; N,6.50. C₂₀ H₃₀ N₂ O₄ S₂ ; 0.10 CH₂ Cl₂ requires C,55.48; H,7.00; N,6.44%. δ(CDCl₃): 1.38(3H,t), 1.50-1.90(5H,m), 2.22(1H,m), 2.60-2.80(3H,m), 2.90-3.35(12H,m), 3.48(1H,m), 5.30(0.20H,s,CH₂ Cl₂), 6.98-7.10(2H,m), 7.30(1H,d), 7.44(1H,s), 8.22(1H,br s).

The following twelve compounds were obtained from Preparation 5, 6 or 7, employed either as the free base or hydrochloride, using an appropriate "Michael acceptor" as alkylating agent, the required amount of triethylamine as acid scavenger, and a suitable solvent such as dimethylformamide, N,N-dimethylacetamide or 1,2-dimethoxyethane, by procedures similar to that described in Example 30.

EXAMPLE 31

5-(2-Ethylsulphonylethyl)-3-[N-{3-oxo-1-butyl)-2(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a gum, using Preparation 5 and methyl vinyl ketone. Rf 0.21 (SS 4). [α]_(D) ²⁵ +19° (c=0.1, CH₃ OH). Found: C,65.01; H,6.58; N,6.88. C₂₁ H₃₀ N₂ O₃ S requires C, 64.58; H, 7.74; N, 7.17%. δ(CDCl₃): 1.35(3H,t), 1.50-1.80(4H,m), 2.18(3H,s), 2.45-2.76(6H,m), 2.95(2H,q), 3.10-3.38(7H,m.), 6.98-7.03(2H,m), 7.30(1H,d), 7.40(1H,s), 8.22(1H,br s).

EXAMPLE 32

3-[N-(2-t-Butoxycarbonylethyl)-2(R)-pyrrolidinylmethyl]-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a gum, using Preparation 5 and t-butyl acrylate. Rf 0.60 (SS 4). [α]_(D) ²⁵ +42° (c=0.1, CH₃ OH). Found: C,61.97; H,7.67; N,5.93. D₂₄ H₃₆ N₂ O₄ S; 0.25 CH₂ Cl₂ requires C,61.99; H,7.83; N,5.96%. δ(CDCl₃): 1.36(3H,t), 1.40-1.80(13H,m), 2.20(1H,m), 2.45-2.65(5H,m), 2.92(2H,q), 3.10-3.35(7H,m), 5.30(0.50H,s,CH₂ Cl₂), 6.96-7.04(2H,m), 7.30(1H,d), 7.42(1H,s), 8.35(1H,br s).

EXAMPLE 33

5-(2-Ethylsulphonylethyl]-3-{N-[2-(N,N-dimethylcarbamoyl)ethyl]-2(R)-pyrrolidinylmethyl}-1H-indole

Obtained as a foam, using Preparation 5 and N,N-dimethylacrylamide. Rf 0.46 (SS 4). [α]_(D) ²⁵ +39° (c=0.1, CH₃ OH). Found: C,60.49; H,8.02; N,9.77. C₂₂ H₃₃ N₃ O₃ S; 0.33 H20; 0.125 CH₂ Cl₂ requires C,60.92; H,7.84; N,9.63%. δ(CDCl₃): 1.42(3H,t), 1.58-1.90(4H,m), 2.35(1H,m), 2.62-2.75(4H,m), 2.84(1H,m), 2.90-3.05(9H,m), 3.15-3.48(6H,m), 5.30(0.25H,s,CH₂ Cl₂), 7.04-7.10(2H,m), 7.32(1H,d), 7.44(1H,s), 8.22(1H,br s).

EXAMPLE 34

3-[N-(2-Carbamoylethyl)-2(R)-pyrrolidinylmethyl]-5-(2-ethylsulphonylethyl-1H-indole

Obtained as a foam, using preparation 5 and acrylamide. Rf 0.35 (SS

4). [α]_(D) ²⁵ +55° (c=0.1, CH₃ OH). Found: C,59.32; H,7.38; N,9.85. C₂₀ N₃ O₃ S; 0.40 H₂ O; 0.083 CH₂ Cl₂ ; 0.25 C₂ H₅ OH requires C,59.27; H,7.60; N,10.07%. δ(CDCl₃): 1.27(0.75H,t,C₂ H₅ OH), 1.38(3H,t), 1.60-2.00(5H,m), 2.28(1H,m), 2.40(1H,m), 2.55(2H,m), 2.70(1H,m), 2.84(1H,m), 2.95(2H,q), 3.25-3.38(6H,m), 3.65(0.5H,q,C₂ H₅ OH), 5.28(0.17H,s,CH₂ Cl₂), 5.38(1H,br s), 7.04-7.06(2H,m), 7.35(1H,d), 7.45(1H,s), 8.15(2H,br s).

EXAMPLE 35

5-2-Ethylsulphonylethyl)-3-N-2-sulphamoylethyl)-2(R)-pyrrolidinylmethyl]-1H-indole

Obtained as a foam, using preparation 5 and vinyl sulphonamide. Rf 0.37 (SS 4). [α]_(D) ²⁵ +48° (c=0.1, CH₃ OH). Found: C,52.67; H,6.92; N,9.39. C₁₉ H₂₉ N₃ O₄ S₂ ; 0.10 CH₂ Cl₂ requires C,52.60; H,6.75; N,9.64%. δ(CDCl₃): 1.42(3H,t), 1.55-1.95(5H,m), 2.30(1H,m), 2.70-2.87(2H,m), 2.95(2H,q), 3.14-3.40(7H,m), 3.62(2H,m), 5.10-5.70(2H,br s), 5.30(0.20H,s,CH₂ Cl₂), 7.06(1H,d), 7.15(1H,s), 7.35(1H,d), 7.48(1H,s), 8.10(1H,br s).

EXAMPLE 36

5-2-Ethylsulphonylethyl)-3-N-2-2-pyridyl)ethyl]-2(R)-pyrrolidinylmethyl}-1H-indole

Obtained as a foam, using preparation 5 and 2-vinylpyridine. Rf 0.57 (SS 4). [α]_(D) ²⁵ +28° (c=0.1, CH₃ OH). Found: C,65.97; H,7 .34; N,9.62. C₂₄ H₃₁ N₃ O₂ S; 0.67 H₂ O requires C,65.86; H,7.45; N,9.60%. δ(CDCl₃): 1.42(3H,t), 1.65-2.00(4H,m), 2.55(1H,m), 2.75-3.05(5H,m), 3.14-3.35(7H,m), 3.42-3.54(2H,m), 7.05-7.10(2H,m), 7.15-7.28(2H,m), 7.35(1H,d), 7.46(1H,s), 7.65(1H,dd), 8.20(1H,br s), 8.56(1H,d).

EXAMPLES 37A AND 37B

5-(2-Ethylsulphonylethyl)-3-{N-[2(R)-phenylsulphinylethyl]-2(R)-pyrrolidinylmethyl}-1H-indole and

5-(2-Ethylsulphonylethyl)-3-{N-[2(S)-phenylsulphinylethyl]-2(R)-pyrrolidinylmethyl}-1H-indole

The mixture of diastereoisomers obtained using Preparation 5 and phenyl vinyl sulphoxide was resolved by conventional column chromatography on silica gel to afford the title compounds as diastereoisomer 1 and diastereoisomer 2. However, which diastereoisomer corresponds with which title compound was not established.

Diastereoisomer 1

Obtained as a foam. Rf 0.52 (SS 4). [α]_(D) ²⁵ +117° (c=0.1, CH₃ OH). Found: C,63.74; H,6.57; N,5.72. C₂₅ H₃₂ N₂ O₃ S₂ requires C, 63.53; H, 6.82; N, 5.93%. δ(CDCl₃): 1.42(3H,t), 1.60-1.95(5H,m), 2.30(1H,m), 2.65(1H,m), 2.85(1H,m), 2.94-3.10(4H,m), 3.20-3.40(6H,m), 3.60(1H,m), 7.05(1H,d), 7.20(1H,br s), 7.32(1H,d), 7.48(1H,s), 7.55-7.60(3H,m), 7.66-7.70(2H,m), 8.13(1H,br s).

Diastereoisomer 2

Obtained as a foam. Rf 0.48(SS 4). [α]_(D) ²⁵ -37° (c=0.1, CH₃ OH). Found: 62.39; H,6.29; N,5.34. C₂₅ H₃₂ N₂ O₃ S₂ ; 0.14 CH₂ Cl₂ requires C,62.28; H,6.66; N,5.78. δ(CDCl₃): 1.42(3H,t), 1.55-1.95(4H,m), 2.35(1H,m), 2.65(1H,m), 2.70(1H,m), 2.94-3.20(6H,m), 3.25-3.40(6H,m), 5.30(0.28H,s,CH₂ Cl₂), 7.05-7.10(2H,m), 7.35(1H,d), 7.40(1H,s), 7.56(3H,m), 7.65-7.70(2H,m), 8.19(1H,br s).

EXAMPLE 38

3-[N-(3-Oxo-1-butyl)-2-(R)-pyrroldinylmethyl]-5-(2phenylsulphonylethyl)-1H-indole

Obtained as a gum, using Preparation 6 and methyl vinyl ketone. Rf 0.60 (SS 4). [α]_(D) ²⁵ +6° (c=0.1, CH₃ OH). Found: C,67.64; H,6.86; N,6.20. C₂₅ H₃₀ ₂ O₃ S; 0.10 CH₂ Cl₂ requires C,67.43; H,6.81; N,6.27%. δ(CDCl₃): 1.45-1.80(4H,m), 2.20(3H,s), 2.42-2.74(5H,m), 3.15-3.20(5H,m), 3.25-3.35(1H,m), 3.40-3.42(2H,m), 5.30(0.20H,s,CH₂ Cl₂), 6.92(1H,d), 7.00(1H,d), 7.22-7.38(2H,m), 7.55-7.70(3H,m), 7.96(2H,d), 8.08(1H,br s).

EXAMPLE 39

3 -{N-[2-(N,N-Dimethylcarbamoyl)ethyl]-2(R)-pyrroldinylmethyl}-5-(2-phenylsulphonvlethyl)-1H-indole

Obtained as a foam, using Preparation 6 and N,N-dimethylacrylamide. Rf 0.40 (SS 4). [α]_(D) ²⁵ +33° (c=0.1, CH₃ OH). Found:C,65.75; H,7.07; N,8.83. C₂₆ H₃₃ N₃ O₃ ; 0.05 CH₂ Cl₂ ; 0.25 H₂ O requires C,65.68; H,7.11; N,8.82%. δ(CDCl₃): 1.48-1.96(4H,m), 2.20-2.35(1H,m), 2.50-2.80(5H,m), 2.98(3H,s), 3.04(3H,s), 3.10-3.48(7H,m), 5.30(0.10H,s,CH₂ Cl₂), 6.92(1H,d), 7.02(1H,s), 7.22(1H,d), 7.30(1H,s), 7.52-7.70(3H,m), 7.94-8.05(3H,m).

EXAMPLE 40

5-Bromo-3-{N-[2-(N,N-dimethylcarbamoyl)ethyl]-2(R)-pyrrolidinylmethyl}-1H-indole

Obtained as a foam, using Preparation 7 and N,N-dimethylacrylamide. Rf 0.58 (SS 4). Found: C,55.53; H,6.18; N,10.66. C₁₈ H₂₄ BrN₃ O; 0.20 CH₂ Cl₂ requires C,55.30; H,6.22; N,10.63%. δ(CDCl₃): 1.52-1.90(4H,m), 2.24-2.43(1H,m), 2.55-2.90(5H,m), 2.95(3H,s), 3.02(3H,s), 3.08-3.20(1H,s), 3.24-3.43(2H,m), 5.30(0.40H,s,CH₂ Cl₂), 7.05(1H,s), 7.22-7.28(2H,m), 7.70(1H,s), 8.30(1H,br s).

EXAMPLE 41

5-Bromo-3-{N-[2-(N-methylcarbamoyl)ethyl]-2(R)-pyrrolidinylmethyl}- 1H-indole

Obtained as a foam, using Preparation 7 and N-methylacrylamide. Rf 0.54 (SS 4). [α]_(D) ²⁵ +66° (c=0.1, CH₃ OH). Found: C,55.53; H,5.96; N,11.42. C₁₇ H₂₂ BrN₃ O requires C,56.05; H,6.09; N,11.53%. δ(CDCl₃): 1.53-1.90(4H,m), 2.16-2.30(1H,m), 2.32-2.64(5H,m), 2.74(3H,d), 3.03-3.15(1H,m), 3.17-3.30(2H,m), 7.02(1H,d), 7.16-7.31(2H,m), 7.69(1H,s), 8.08-8.30(2H,br m).

EXAMPLE 42

3- (N-Cyclopentylmethyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethyl)-1H-indole

Obtained as a foam by a procedure similar to that described in Example 18 (b), using Preparation 5 and cyclopentanecarboxylic acid. Rf 0.60 (SS 4). Found: C,67.74; H,8.55; N,6.81. C₂₃ H₃₄ N₂ O₂ S; 0.10 CH₂ Cl₂ requires C,67.59; H,8.36; N,6.79. δ(CDCl₃): 1.10-1.95(14H,m), 2.08-2.22(1H,m), 2.30-2.42(2H,m), 2.70-2.98(6H,m), 3.16-3.50(6H,m), 5.30(0.20H,s), 7.02(1H,d), 7.10(1H,s), 7.32(1H,d), 7.42(1H,s), 8.35(1H,br s).

EXAMPLE 43

5-(2-Ethylsulphonylethyl)-3-{N-[2-(N-methylcarbamoyl)ethyl]-2(R)-pyrrolidinylmethyl}-1H-indole

A solution of trifluoroacetic acid (0.25 ml) in dichloromethane (2 ml) was added to a stirred, ice-cold solution of 3-[N-(2-t-butoxycarbonylethyl)-2(R)pyrrolidinylmethyl]-5-(2-ethylsulphonylethyl)-1H-indole (Example 32; 250 mg). After 1 hour, the cooling bath was removed and stirring continued for 18 hours at room temperature. More trifluoroacetic acid (0.5 ml) was added, stirring continued for a further 8 hours, then evaporation under reduced pressure effected. Residual trifluoroacetic acid was removed from the crude product by azeotropic evaporation under reduced pressure using, sequentially, dichloromethane, ethyl acetate and dichloromethane, to provide a gum.

A sample of this crude carboxylic acid (100 mg) was stirred, together with 1-hydroxybenzotriazole (30 mg), N-methylmorpholine (0.1 ml) and 1-ethyl-3-dimethylaminopropylcarbodiimide hydrochloride (50 mg), in dichloromethane (5 ml) with ice-bath cooling. After 10 minutes methylamine hydrochloride (15 mg) was added, and stirring continued at 0° C. for 1 hour then at room temperature for 18 hours. The reaction mixture was diluted with dichloromethane, washed with water (2×), dried (Na₂ SO₄) and evaporated under reduced pressure to afford the crude product as an oil. Purification was effected by column chromatography on silica gel, eluting with a solution of ethanol in dichloromethane (0 to 10% ethanol), to give the title compound (32 mg) as a gum. Rf 0.35 (SS4). [α]_(D) ²⁵ +34° (c=0.1, CH₃ OH). Found: C,60.58; H,7.39; N,9.36. C₂₁ H₃₁ N₃ O₃ S; 0.20 CH₂ Cl₂ requires C,60.26; H,7.49; N,9.94%. δ(CDCl₃): 1.35(3H,t), 1.55-1.94(4H,m), 2.20-2.85(9H,m), 2.90(2H,q), 3.08-3.44(6H,m), 3.65(1H,m), 5.30(0.40 H,s,CH₂ Cl₂), 7.00-7.08(2H,m), 7.32(1H,d), 7.40(1H,s), 8.15(1H,br s), 8.44(1H,m).

EXAMPLE 44

3-(N-Cyclopropylmethyl-2(R)-pyrrolidinomethyl)-5-(2-sulphamoylethenyl)-1H-indole

Obtained as a foam by a procedure similar to that described in Preparation 3, using Example 23 and vinyl sulphonamide. Rf 0.19 (SS 6). [α]_(D) ²⁵ +59° (c=0.1, CH₃ OH). Found: C,61.47; H,7.11; N,11.18. C₁₉ H₂₅ N₃ O₂ S; 0.18 CH₂ Cl₂ requires C,61.47; H,6.82; N,11.20%. δ(CDCl₃ /CD₃ OD): 0.06-0.15(2H,m), 0.42-0.54(2H,m), 0.80-0.90(1H,m), 1.42-1.80(4H,m), 1.88-2.00(1H,m), 2.16-2.30(1H,m), 2.42-2.65(2H,m), 2.84-2.94(1H,m), 3.04-3.10 (1H,m), 3.28-3.40(1H,m), 5.20(0.36H,s,CH₂ Cl₂), 6.78 (1H,d), 6.98(1H,s), 7.18-7.32(2H,m), 7.48(1H,d), 7.55(1H,s).

PREPARATION 1

3-(N-Benzyloxycarbonyl-2(R)-pyrrolidinylcarbonyl)-5-bromo-1H-indole

Two solutions containing the reactants were prepared separately as follows. To a stirred solution of N-benzyloxycarbonyl-R-proline (1.0 g) in dry dichloromethane (2 ml) and dimethylformamide (1 drop) was added oxalyl chloride (0.5 ml), and the resulting solution was stirred at room temperature for 1.5 hours. The solution was evaporated under reduced pressure and the remaining solvent was removed under high vacuum to give the N-benzyloxycarbonyl-R-proline acid chloride. Concurrently, a solution of ethyl magnesium bromide (1.4 ml of a 3M solution in ether) was added dropwise over 5 minutes to a stirred solution of 5-bromoindole (0.75 g) in dry ether (18 ml). The mixture was stirred at room temperature for 10 minutes, heated under reflux for 2 hours, cooled to -30° C., and then a solution of the above N-benzyloxycarbonyl-R-proline acid chloride in dry ether (4 ml) added dropwise, after which stirring was continued for a further 1 hour. Ether (12.5 ml) and saturated aqueous sodium bicarbonate solution (6.5 ml) were then added and the temperature was allowed to rise to room temperature. Stirring was continued for a further 10 minutes and the mixture was filtered under reduced pressure. The solid was washed with ethyl acetate, then the combined filtrate and washings were washed with water and brine, then dried (MgSO₄). Evaporation under reduced pressure of the solvent gave an oil which was chromatographed on silica gel. Elution with ethyl acetate gave the title compound as a foam (0.82 g). [α]_(D) ²⁵ +89° (c=0.1, CH₃ OH). Found: C,58.85; H,4.51; N,6.38. C₂₁ H₁₉ BrN₂ O₃ requires C,59.02; H,4.48; N,6.56%. LRMS: m/z (relative intensity) 428 (M⁺ with ¹⁸ Br,5), 426 (M⁺ with ⁷⁹ Br, 5), 224 (19), 222 (21), 204 (62), 160 (68), 91 (100).

PREPARATION 2

3-(N-Benzyloxycarbonyl-2(R)-pyrrolidinylmethyl)-5-bromo-1H-indole

3-(N-Benzyloxycarbonyl-2(R)-pyrrolidinylcarbonyl)-5-bromo-1H-indole (Preparation 1; 0.67 g, 1.57 mmol) was dissolved in dry tetrahydrofuran (20 ml) and, at room temperature under nitrogen, lithium borohydride (2M solution in tetrahydrofuran; 1.2 ml, 2.4 mmol) was added. The reaction mixture was stirred at room temperature for 3 hours, heated under reflux for 16 hours, then allowed to cool to room temperature. 2N Hydrochloric acid (10 ml) was added dropwise and the reaction mixture then partitioned between ethyl acetate and water. The separated organic phase was washed with saturated aqueous sodium bicarbonate solution (2×) and brine (1×), dried (Na₂ SO₄), and evaporated under reduced pressure to give a colourless oil. Purification by column chromatography on silica gel, eluting with dichloromethane, gave the title compound as an oil (0.32 g). Rf 0.20 (SS 1). Found: C,59.94; H,5.07; N,6.58. C₂₁ H₂₁ BrN₂ O₂ ; 0.10 CH₂ Cl₂ requires C,60.08; H,5.07; N,6.64%. δ(CDCl₃)--mixture of rotamers: 1.63-1.90(4H,m), 2.60-2.82(1H,m), 3.10-3.28(1H,m), 3.30-3.54(2H,m), 4.18(1H,m), 5.15-5.25(2H,m), 5.30(0.2H,s,CH₂ Cl₂), 6.90 and 6.95(1H, 2×s), 7.05-7.50(7H,m), 7.70 and 7.85(1H, 2×s), 8.25(1H,br s).

PREPARATION 3

3-(N-Benzyloxycarbonyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethenyl)-1H-indole

A stirred mixture of 3-(N-benzyloxycarbonyl-2(R)-pyrrolidinylmethyl)-5-bromo-1H-indole (Preparation 2; 0.43 g, 1.04 mmol), ethyl vinyl sulphone (0.17 g, 1.4 mmol), tri-o-tolylphosphine (91 mg), palladium(II) acetate (16 mg), triethylamine (0.31 ml) and acetonitrile (4 ml), under nitrogen, was heated under reflux for 18 hours, allowed to cool, then evaporated under reduced pressure. The residue was purified by column chromatography on silica gel, eluting with a dichloromethane to dichloromethane:ethanol (99:1) gradient, to afford the title compound as a foam (0.34 g). Rf 0.80 (SS 2). [α]_(D) ²⁵ -50° (c=0.1, CH₃ OH). Found: C,65.16; H,6.17; N,5.97. C₂₅ H₂₈ N₂ O₄ S; 0.125 CH₂ Cl₂ requires C,65.15; H,6.15; N,6.05%. δ(CDCl₃)--mixture of rotamers: 1.42(3H,t), 1.70-1.88(4H,m), 2.78(1H,m), 3.05-3.48(5H,m), 4.20(1H,m), 5.16-5.28(2H, br q), 5.30(0.25H,s,CH₂ Cl₂), 6.64-7.82(1H,m), 6.96 and 7.05(1H, 2×s), 7.30-7.45(7H,m), 7.55-7.80 and 8.00(2H, m and s), 8.32(1H,br s).

PREPARATION 4

3-(N-Benzyloxycarbonyl-2(R)-pyrrolidinylmethyl)-5-(2-phenylsulphonylethenyl)-1H-indole

This was obtained by a procedure similar to that described in Preparation 3, but using phenyl vinyl sulphone instead of ethyl vinyl sulphone. The crude product was purified by column chromatography on silica gel, eluting with an ethyl acetate in hexane gradient (20 to 60% ethyl acetate), to afford the title compound as a foam. Rf 0.30 (SS 3). [α]_(D) ²⁵ -57° (c=0.1, CH₃ OH). Found: C,69.62; H,5.62; N,5.58. C₂₉ H₂₈ N₂ O₄ S requires C,69.58; H,5.64; N,5.59%. δ(CDCl₃)--mixture of rotamers: 1.70-1.90(4H,m), 2.72(1H,m), 3.16-3.50(3H,m), 4.18(1H,m), 5.18(2H,q), 6.70-7.00(2H,m), 7.28-7.60(10H,m), 7.68-8.00(4H,m), 8.25(1H,br s).

PREPARATION 5

5-(2-Ethylsulphonylethyl)-3-(2(R)-pyrrolidinylmethyl)-1H-indole

A solution of 3-(N-benzyloxycarbonyl-2(R)-pyrrolidinylmethyl)-5-(2-ethylsulphonylethenyl)-1H-indole (Preparation 3; 160 mg, 0.35 mmol) in ethanol (5 ml) was hydrogenated over 10% palladium on charcoal (150 mg) at 15 p.s.i. (1.04 bar) and room temperature for 18 hours, and then filtered. Evaporation of the filtrate under reduced pressure yielded a foam which was purified by column chromatography on silica gel, eluting with a gradient of 0.880 aqueous ammonia: methanol:dichloromethane (0:10:90 to 1:10:90), to provide the title compound as a foam (70 mg). Rf 0.30 (SS 4). [α]_(D) ²⁵ -11° (c=0.1, CH₃ OH). Found: C,63.13; H,7.37; N,8.55. C₁₇ H₂₄ N₂ O₂ S; 0.05 CH₂ Cl₂ requires C,63.07; H,7.48; N,8.63%. δ(CDCl₃): 1.35(3H,t), 1.65-1.90(5H,m), 2.70-3.10(6H,m), 3.25(4H,m), 3.35(1H,m), 5.25(0.10H,s, CH₂ Cl₂), 6.98-7.04(2H,m), 7.22(1H,d), 7.45(1H,s), 8.12(1H,br s).

The hydrochloride salt was obtained by conducting the above hydrogenation in the presence of acetyl chloride (1.1 equiv.) and, after filtration of the reaction mixture and evaporation of the filtrate under reduced pressure, the crude salt was of sufficient purity for use in subsequent reactions.

PREPARATION 6

5-(2-Phenylsulphonylethyl)-3-(2(R)-pyrrolidinylmethyl)1H-indole

The crude hydrochloride salt (2.2 g) of the title compound was obtained by a procedure similar to that described in Preparation 5, using 3-(N-benzyloxycarbonyl-2(R)-pyrrolidinylmethyl)-5-(2-phenylsulphonylethenyl)-1H-indole (Preparation 4; 2.81 g, 5.6 mmol), and was sufficiently pure for use in subsequent reactions.

A sample (300 mg) was partitioned between ethyl acetate and 2M aqueous sodium carbonate solution. The separated organic phase was washed with brine, dried (Na₂ SO₄) and evaporated under reduced pressure to provide a white foam (270 mg). The crude free base was purified by column chromatography on silica gel, eluting initially with dichloromethane followed by a gradient of 0.880 aqueous ammonia:methanol: dichloromethane (0:10:90 to 1:10:90), to furnish the title compound as a foam. Rf 0.15 (SS 4). [α]_(D) ²⁵ -7° (c=0.1, CH₃ OH). Found: C,66.66; H,6.27; N,7.40. C₂₁ H₂₄ N₂ O₂ S; 0.50 H₂ O requires C,66.81; H,6.68; N,7.42%. δ(CDCl₃): 1.42(1H,m), 1.65-1.95(3H,m), 2.60(2H,br s, including 0.50 H₂ O), 2.75-3.20(6H,m), 3.30-3.45(3H,m), 6.84(1H,d), 7.02(1H,s), 7.25(1H,d), 7.30(1H,s), 7.52-7.70(3H,m), 7.92(2H,d), 8.30(1H,br s).

PREPARATION 7

5-Bromo-3-(2(R)-pyrrolidinylmethyl)-1H-indole

The title compound was prepared by either of the following methods.

(a)

A mixture of the title compound of Preparation 2 (10.0 g, 24.2 mmol) and a solution of hydrogen bromide in glacial acetic acid (36% w/w; 17 ml) was stirred at about 0° C. for 1 hour, then the solvent removed under reduced pressure and the residue azeotroped with toluene. The resulting oil was partitioned between dichloromethane and 2M aqueous sodium carbonate solution, then the organic phase separated, combined with a further dichloromethane extract of the aqueous phase, dried (Na₂ SO₄) and evaporated under reduced pressure. Purification of the crude product by column chromatography on silica gel, eluting with a solvent gradient of 0.880 aqueous ammonia:methanol: dichloromethane (0:5:95 to 2:5:95), gave the title compound as an oil (2.01 g). Rf 0.10 (SS 4). [α]_(D) ²⁵ -9° (c=0.1, CH₃ OH). Found: C,54.75; H,5.41; N,9.63. C₁₃ H₁₅ BrN₂ ; 0.20 CH₂ Cl₂ requires C,54.84; H,5.37; N,9.67%. δ(CDCl₃): 1.35-1.50(1H,m), 1.68-1.98(3H,m), 2.45(1H,br s), 2.72-2.92(3H,m), 2.96-3.08(1H,m), 3.28-3.43(1H,m), 5.28(0.40H,s,CH₂ Cl₂), 7.06(1H,s), 7.18-7.26(2H,m), 7.72(1H,s), 8.52(1H,br s).

(b)

A solution of the title compound of Preparation 2 (5.0 g, 12.1 mmol) in dichloromethane was added dropwise to a stirred mixture of boron trifluoride etherate (17.15 g, 14.9 ml, 12.1 mmol) and ethanethiol (21.4 g, 25.5 ml, 344 mmol) at room temperature under nitrogen. After 68 hours the reaction mixture was poured into 10% aqueous sodium carbonate solution, then extraction with ethyl acetate (3×400 ml) effected. Evaporation under reduced pressure of the dried (Na₂ SO₄), combined extracts, followed by column chromatography on silica gel of the crude product, eluting with 0.880 aqueous ammonia:methanol: dichloromethane (1:10:90), provided the title compound as a foam (2.10 g). Rf 0.10 (SS 4). [α]_(D) ²⁵ -12° (c=0.1, CH₃ OH). Found: C,55.04; H,5.29; N,9.83. C₁₃ H₁₅ BrN₂ ; 0.06 CH₂ Cl₂ requires C,55.10; N,5.35; N,9.83%. δ(CDCl₃): 1.38-1.50(1H,m), 1.68-1.98(3H,m), 2.32(1H,br s), 2.76-2.90(3H,m), 3.00-3.10(1H,m), 3.32-3.41(1H,m), 5.30(0.12H,s,CH₂ Cl₂), 7.06(1H,s), 7.22-7.30(2H,m), 7.75(1H,s), 8.37(1H,br s).

Biological Activity

The following Table illustrates the in vitro activities for a range of the Compounds of the invention on dog isolated saphenous vein strip. EC₅₀ represents the concentration of compound which causes 50% of the maximum contraction effected by it.

                  TABLE                                                            ______________________________________                                                                RELATIVE POTENCY                                                               EC.sub.50 (compound)/                                   EXAMPLE     EC.sub.50 (M)                                                                             EC.sub.50 (5-HT)                                        ______________________________________                                          1          4.3 × 10.sup.-7                                                                     9.4                                                      4          1.2 × 10.sup.-7                                                                     2.3                                                      8          1.9 × 10.sup.-7                                                                     2.5                                                      9          8.2 × 10.sup.-8                                                                     1.8                                                     13          7.1 × 10.sup.-8                                                                     1.4                                                     21          5.6 × 10.sup.-7                                                                     4.9                                                     26          1.6 × 10.sup.-7                                                                     3.8                                                     31          3.1 × 10.sup.-8                                                                     1.9                                                     34          6.2 × 10.sup.-8                                                                     1.4                                                     36          2.9 × 10.sup.-7                                                                     11.0                                                    37A         2.9 × 10.sup.-7                                                                     4.6                                                     (diastereoisomer 1)                                                            38          4.4 × 10.sup.-7                                                                     3.4                                                     44          1.8 × 10.sup.-7                                                                     2.7                                                     ______________________________________                                    

Safety Profile

Several of the compounds of the invention have been tested in conscious dogs, for example Examples 8 and 13, and showed no signs of adverse acute toxicity at doses of up to 1 mg/Kg i.v. 

We claim:
 1. A compound of formula (I): ##STR18## or a pharmaceutically acceptable salt thereof, wherein R¹ is (R³ CO)C₁ -C₃ alkylene; (R⁴ O₂ C)C₁ -C₃ alkylene; (R⁵ R⁶ NOC)C₁ -C₃ alkylene; (R⁵ R⁶ NO₂ S)C₁ -C₃ alkylene; (R³ S(O)_(m))C₁ -C₃ alkylene; (R⁷ O)C₁ -C₄ alkylene; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; (heteroaryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl optionally substituted with HO; C₃ -C₆ alkenyl optionally substituted with aryl; C₅ -C₇ cycloalkenyl; or C₃ -C₆ alkynyl;R² is H; halo; F₃ C; NC; R⁸ R⁹ NOC; (R⁸ R⁹ NOC)C₁ -C₃ alkylene; R⁸ R⁹ NO₂ S; (R⁸ R⁹ NO₂ S)C₁ -C₃ alkylene; R¹⁰ S(O)_(m) ; (R¹⁰ S(O)_(m))C₁ -C₆ alkylene; R¹² CON(R¹¹); R¹² CON(R¹¹)]C₁ -C₃ alkylene; R¹⁰ SO₂ N(R¹¹); (R¹⁰ SO₂ N(R¹¹))C₁ -C₃ alkylene; R¹⁰ R⁹ NOCN (R¹¹); (R⁸ R⁹ NOCN (R¹¹))C₁ -C₃ alkylene; R¹⁰ O₂ CN (R¹¹); (R¹⁰ O₂ CN(R¹¹))C₁ -C₃ alkylene; or R¹³ (CH₂)_(n) CH═CH; R³ is C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl; or aryl; R⁴ is C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; or C₃ -C₇ cycloalkyl; R⁵ and R⁶ are each independently selected from H; C₁ -C₃ alkyl; (C₃ -C₇ cycloalkyl) C₁ -C₃ alkylene; (aryl) C₁ -C₃ alkylene; and C₃ -C₇ cycloalkyl; R⁵ and R⁶ together with the nitrogen atom to which they are attached form a 4- to 7-membered heterocyclic ring which may optionally incorporate a further heteroatom linkage selected from O, S(O)_(m), NH, N(C₁ -C₄ alkyl), and N(C₁ -C₅ alkanoyl); R⁷ is H; C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl; or aryl; R⁸ and R⁹ are each independently selected from H; C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; and C₃ -C₇ cycloalkyl; R⁸ and R⁹ together with the nitrogen atom to which they are attached form a 4- to 7-membered heterocyclic ring which may optionally incorporate a further heteroatom linkage selected from O, S(O)_(m), NH, N(C₁ -C₄ alkyl), and N(C₁ -C₅ alkanoyl); R¹⁰ is C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl; or aryl; R¹¹ and R¹² are each independently selected from H; C₁ -C₆ alkyl; (C₃ -C₇ cycloalkyl)C₁ -C₃ alkylene; (aryl)C₁ -C₃ alkylene; C₃ -C₇ cycloalkyl; and aryl; R¹³ is selected from R⁵ R⁹ NOC; R⁸ R⁹ NO₂ S; R¹⁰ S(O)_(m) ; R¹² CON(R¹¹); R¹⁰ SO₂ N(R¹¹); R⁸ R⁹ NOCN(R¹¹); and R¹⁰ O₂ CN(R¹¹); wherein R⁸, R⁹, R¹⁰, R¹¹ and R¹² are as defined above; and k, m and n are each independently selected from 0, 1 and 2, with the proviso that when m is O, R¹⁰ is not aryl.
 2. A compound as claimed in claim 1 wherein R¹ is (R³ CO)C₁ -C₂ alkylene; (R⁴ O₂ C)C₁ -C₂ alkylene; (R⁵ R⁶ OC)C₁ -C₂ alkylene; R⁵ R⁶ NO₂ SCH₂ CH₂ ; (R³ S(O)_(m))C₁ -C₂ alkylene; (R⁷ O)C₂ -C₃ alkylene; (C₃ -C₇ cycloalkyl)CH₂ ; (phenyl)C₁ -C₂ alkylene; (pyridyl)C₁ -C₂ alkylene; C₅ -C₆ cycloalkyl optionally substituted with HO; C₃ -C₅ alkenyl optionally substituted with phenyl; or cyclohexenyl; R² is R⁹ NHOC; (R⁹ NHOC)C₁ -C₂ alkylene; R⁹ NHO₂ S; (R⁹ NHO₂ S)C₁ -C₂ alkylene; R¹⁰ SO₂ ; (R¹⁰ SO₂)C₁ -C₂ alkylene; R¹² CONH; (R¹² CONH)C₁ -C₂ alkylene; R¹⁰ SO₂ NH; (R¹⁰ SO₂ NH)C₁ -C₂ alkylene; or R¹³ CH═CH; R³ is C₁ -C₆ alkyl or aryl; R⁴ is C₁ -C₆ alkyl or (aryl)C₁ -C₃ alkylene; R⁵ and R⁶ are each independently selected from H or C₁ -C₆ alkyl; R⁷ is H or C₁ -C₆ alkyl; k is 1; and m is 1 or
 2. 3. A compound as claimed in claim 2 wherein R¹ is R³ COCH₂ ; R³ COCH₂ CH₂ ; R⁴ O₂ CCH₂ ; R⁴ O₂ CCH₂ CH₂ ; R⁵ R⁶ NOCCH₂ ; R⁵ R⁶ NOCCH₂ CH₂ ; R⁵ R⁶ NOCCH(CH₃); R⁵ R⁶ NO₂ SCH₂ CH₂ ; R³ S(O)_(m) CH₂ CH₂ ; R⁷ OCH₂ CH₂ ; R⁷ OCH(CH₃)CH₂ ; R⁷ OCH₂ CH₂ CH₂ ; cyclopropylCH₂ ; cyclobutylCH₂ ; cyclopentylCH₂ ; benzyl; phenylCH₂ CH₂ ; phenylCH(CH₃); pyridylCH₂ ; pyridylCH₂ CH₂ ; cyclopentyl; hydroxycyclopentyl; allyl; pentenyl; cinnamyl; or cyclohexenyl; R² is R¹⁰ SO₂ CH₂ CH₂ or R⁹ NHO₂ SCH═CH; R³ is methyl or phenyl; R⁴ is (CH₃)₃ C or benzyl; R⁵ and R⁶ are each independently selected from H or methyl; R⁷ is H or methyl; R⁹ is H or C₁ -C₆ alkyl; and R¹⁰ is C₁ -C₆ alkyl or aryl.
 4. A compound as claimed in claim 3 wherein R¹ is CH₃ COCH₂ CH₂ ; (CH₃)₃ CO₂ CCH₂ CH₂ ; benzylO₂ CCH₂ ; H₂ NOCCH₂ CH₂ ; CH₃ NHOCCH₂ CH₂ ; (CH₃)₂ NOCCH₂ CH₂ ; H₂ NO₂ SCH₂ CH₂ ; phenylSOCH₂ CH₂ ; HOCH₂ CH₂ ; CH₃ OCH₂ CH₂ ; cyclopropylCH₂ ; cyclobutylCH₂ ; cyclopentylCH₂ ; phenylCH(CH₃); 2-pyridylCH₂ ; 4-pyridylCH₂ ; 2-pyridylCH₂ CH₂ ; cyclopentyl; 2-hydrocyclopentyl; allyl; 3-methyl-2-butenyl; cinnamyl; or 3-cyclohexenyl; and R² is CH₃ CH₂ SO₂ CH₂ CH₂ ; phenylSO₂ CH₂ CH₂ or H₂ NO₂ SCH═CH.
 5. A compound as claimed in claim 1 wherein the compound has the formula (IA): ##STR19##
 6. A pharmaceutical composition comprising a compound of formula (I), or a pharmaceutically acceptable salt thereof, as claimed in claim 1, together with a pharmaceutically acceptable diluent or carrier.
 7. A method of treating a human being for migraine cluster headache, chronic paroxysmal hemicrania or headache associated with a vascular disorder, or depression, anxiety, an eating disorder, obesity or drug abuse, which comprises treating said human being with an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition as claimed in claim
 1. 8. A method of treating a human being for a medical condition for which a selective agonist of 5-HT₁ -like receptors is indicated, which comprises treating said human being with an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition as claimed in claim
 1. 